In the present work, the wire electrical discharge machining (WEDM) process of the 65 vol% SiCp/2024Al composite prepared by pressure infiltration methods has been investigated. The microstructure of the machined composite was characterized by scanning electron microscope, the average surface roughness (Ra), X-ray diffraction, X-ray photoelectron spectroscopy and transmission electron microscopy (TEM) techniques. Three zones from the surface to the interior (melting zone, heat affected zone and un-affected zone) were found in the machined composites, while the face of SiC particles on the surface toward the outside was “cut” to be flat. Increase in Al and Si but decrease in C and O were observed in the core areas of the removed particles. Si phase, which was generated due to the decomposition of SiC, was detected after the WEDM process. The irregular and spherical particles were further observed by TEM. Based on the microstructure observation, it is suggested that the machining mechanism of 65 vol% SiCp/2024Al composite was the combination of the melting of Al matrix and the decomposition of SiC particles.

The precipitation sequence of 6061Al has changed after introducing high amount SiC nanowires due to the serious segregation of Mg element. In the present work, 0.8 wt% Mg element was added into 6061Al matrix to compensate the segregation effect, and the 15 vol% SiCnw/6061Al+0.8Mg composite was prepared by pressure infiltration method. Regardless of aging time, the hardness of SiCnw/6061Al composite could be improved by the addition of Mg. MgAl2O4 phase at SiC nanowire-Al matrix interface was found in SiCnw/6061Al+0.8Mg composite after solid solution treatment. The ultimate precipitate of Al matrix in SiCnw/6061Al+0.8Mg composite has been restored from B′ (MgSi>1) to β (Mg2Si). Moreover, the hardness of composites was improved 10% after addition of Mg in the over-aging status, implying that the strengthening effect of B′ phase might be inferior to that of β' and β phases. Due to early failure behavior, the tensile strength of the peak-aged composites was slightly decreased by the addition of Mg element. However, the yield strength of the composites was improved, which could be well explained by the modified shear-lag model. It is suggested that addition of extra alloying elements to compensate the segregation effect might be an effect method to improve the yield strength. However, for the application favor high tensile strength, design of performance matching in elastic-plastic behavior between matrix and reinforcement and the ability of Al matrix to relax the stress concentration might be the advisable choice.

•Effective heat treatment temperature can be got from temperature dependent Raman spectra.•The Raman bands of ZrW2O8 will suffer frequency shift under thermal stress and different bands show diverse trends.•The Raman frequency shift can be estimated and in good agreement with experimental results.•We establish a novel method to measure NTE materials' CTE by measuring Raman frequency shift and Grüneisen parameter.Negative thermal expansion materials with open frame structure were easy to undergo phase transformation under high thermal mismatch stress. In this work, a large amount of γ-phase was found in ZrW2O8/Al composite, presenting great fluctuations. Based on the temperature-dependent Raman spectroscopy and theoretical calculation, the accurate heat-treatment temperature was used to eliminate γ-phase and low thermal expansion composite without abnormal expansion was obtained. The Raman frequency shift caused by the thermal stress was quantitatively analyzed. The negative thermal expansion material's thermal expansion was estimated with Raman peak shift.Download high-res image (276KB)Download full-size image

In the present work, microstructure and mechanical performance of extruded SiCnw/Al composites have been investigated. The extrusion treatment leads to the alignment of SiC nanowires and the densification of the composites. The average length of SiC nanowires has been shortened after extrusion. High density dislocation tangles have been observed in Al matrix after extrusion. As the “non-deformable” phases, SiC nanowires inhabited the movement and deformation of surrounding Al matrix, leading to the formation of the grain boundaries. Therefore, SiC nanowires were mainly found at the boundary of Al grains in the extruded composites. Regardless of content of SiC nanowires, the yield strength, tensile strength and elongation of SiCnw/6061Al composites have been improved after extrusion treatment. Based on generalized mixture rule considering the effect of porosity, the increase of elastic modulus of SiCnw/6061Al composites is mainly due to the densification effect. The strengthening factor and efficiency of SiC nanowires are highest among all SiC reinforcements, and the strengthening behavior of SiC reinforced Al matrix composites could be well explain by the modified shear-lag model. The ratio of strengthening efficiency of SiCnw/Al composites before and after extrusion was about 0.6, indicating that orientation optimization of SiC nanowires is an effective method to improve the mechanical properties of SiCnw/Al composites.

Fully dense Y2Mo3O12/Al composites were prepared by squeeze-casting. Relatively mild conditions of 750 °C/20 min/50 MPa were used in order to avoid reaction of the components. SEM, Raman spectroscopy, XRD and dilatometry were used to characterize the microstructures and morphologies of the composites. Zero thermal expansion was achieved in the temperature range where the thermal mismatch strain was zero. We show that the CTE mismatch of Al and Y2Mo3O12 results in compressive and tensile strains that distort the Y2Mo3O12 lattice. We establish a novel method to measure the negative thermal expansion (NTE) materials' CTE under strain by measuring the composites' CTE and calculating the thermal mismatch strain between the NTE ceramic and the metal matrix. The relationship between thermal strain and Raman shift is established and measured and the simulated results are in good agreement. We also find Y2Mo3O12 to have a positive CTE when the surface strain is ≥0.80 × 10−2%.

It has not been reported in the existed literatures that whether it is possible to prepare GNFs/Al composites by pressure infiltration method due to the poor wettability and severe reaction behavior between carbon and molten Al. In the present study, microstructure and mechanical behavior of graphene nanoflakes (GNFs) reinforced Al-20Si (GNFs/Al-20Si) composites prepared by the pressure infiltration method have been thoroughly investigated. The Al-20Si matrix was chosen to inhibit the formation of Al4C3. It has found that the GNFs and Al alloy matrix has been well bonded without formation of Al4C3, which authenticated the effectiveness of the alloying treatment. Moreover, the hardness and the elastic modulus of the composites were increased linearly with the increase in the GNFs content. After addition of 1.5 wt% GNFs, the ultimate tensile strength and bending strength attained the peak values, which increased 130% and 230% to that of Al matrix, respectively. To the best of our knowledge, it is the highest strengthening ratio in Al matrix composites reinforced with graphene reinforcements. Furthermore, based on the modified shear-lag model and combined with the literatures’ data, the strengthening behavior of GNFs/Al composites has been extensively discussed. It is concluded that the pressure infiltration method is the most feasible and successful way to prepare GNFs/Al composites without formation of Al4C3 and with high strengthening ratio.

•Cu(V) film was employed as a self-forming diffusion barrier for Cu metallization.•No Cu3Si peak was detected in Cu(V)/SiO2/Si samples even after annealed at 500 °C.•V atoms were segregated the Cu(V)/SiO2 interface after annealed.•Sharp declines of Cu and Si concentrations indicated a lack of inter-diffusion.•A self-forming layer (8 nm) was observed at the interface after annealed at 400 °C.The properties of Cu(V) alloy films were investigated to evaluate its potential use as self-forming diffusion barrier in copper metallization. Cu(V) alloy films were deposited on SiO2/Si substrates by magnetron sputtering. Cu(V)/SiO2/Si systems were subsequently annealed at various temperatures and analyzed by four-point probe measurement (FPP), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). After annealed at 500 °C, the resistivity of the Cu(V) films reduced to 3.1 μΩ cm, there is no obvious increase in resistivity. XRD suggest that Cu alloy film has preferential (111) crystal orientation and no extra peak corresponding to Cu and Si even after annealed at 500 °C. According to TEM results, a self-formed thin layer with the thickness of about 8 nm is observed at the interface between Cu alloy and the SiO2/Si substrate in the sample annealed at400 °C. As XPS results, after annealed at 400 °C and 500 °C, V atoms are observed at the surface of the Cu(V) films and the interface of the Cu(V) and SiO2/Si. The formation of the self-formed thin layer is probably due to the separation of V at the interface. The sharp declines of the Cu and Si concentrations at the interface indicate a lack of inter-diffusion between Cu and SiO2/Si. Adding small amounts of V to Cu film can improve the barrier performance and thermal stability compared with pure Cu contact systems.

The authors discovered the self-lubrication behavior of TiB2/Al composite and pointed out that the materials responsible for the self-lubrication behavior comes from the oxidation of TiB2. Atomic/friction force microscopy and first-principles calculations have been employed to study the self-lubrication microscopic mechanism of TiB2/Al composite. Atomic force microscopy confirms the existence of a soft film with nanometer thickness on the TiB2 surface, which was attributed to H3BO3 film. Friction measurements revealed much smaller friction force on this H3BO3 nanofilm than that on Al matrix. The detailed structure and interactions among H3BO3 molecules and between the H3BO3 sheet and substrate were explored by density functional theory based calculations. The details of adsorption of H3BO3 sheet on TiB2 and TiO2 surface were scrutinized and the potential of the relative movement between H3BO3 sheets were scanned and compared with that of graphite. The generation of H3BO3 film, the strong chemical adsorption of H3BO3 film on the surface of the composite, the strong hydrogen bonding in H3BO3 film, and small potential in the relative slide between H3BO3 sheets warrant the good self-lubricant properties of TiB2/Al metal matrix composites.Keywords: first-principles calculations; friction measurements; H3BO3 sheets; hydrogen bond; self-lubrication microscopic mechanism; TiB2/Al composite;

•Porous structure of HSS was characterized from sub-millimeter to nano-scale.•Hollow fly ashes and sub-millimeter irregular open cells were found by CT and CSLM.•Micro-sized open cell in gaps between fly ashes showed normal/bimodal distribution.•PG was mainly composed of amorphous Al–O–P nano-pore area and α-Al2O3.•Nano-pores (mainly from 10 to 100 nm) demonstrated a quasi-normal distribution.In the present work, the porous structure of fly ash/phosphate geopolymer hollow sphere structures (FPGHSS), prepared by pre-bonding and curing technology, has been characterized by multi-resolution methods from sub-millimeter to nano-scale. Micro-CT and confocal microscopy could provide the macroscopic distribution of porous structure on sub-millimeter scale, and hollow fly ashes with sphere shape and several sub-millimeter open cells with irregular shape were identified. SEM is more suitable to illustrate the distribution of micro-sized open and closed cells, and it was found that the open cells of FPGHSS were mainly formed in the interstitial porosity between fly ashes. Mercury porosimeter measurement showed that the micro-sized open cell of FPGHSS demonstrated a normal/bimodal distribution, and the peaks of pore size distribution were mainly around 100 and 10 μm. TEM observation revealed that the phosphate geopolymer was mainly composed of the porous area with nano-pores and dense areas, which were amorphous Al–O–P phase and α-Al2O3 respectively. The pore size of nano-pores demonstrated a quasi-normal distribution from about 10 to 100 nm. Therefore, detailed information of the porous structure of FPGHSS could be revealed using multiple methods.

•Novel FPGHSS were prepared by the pre-bonding and curing technology.•Compressive properties of FPGHSS showed a typical character of cellular materials.•Fracture morphology was observed during compression to reveal failure mechanisms.•Microstructures of fly ash, phosphate geopolymer and interface area were observed.•Interface microstructure and its role on the compressive behavior were discussed.In the present work, novel fly ash/phosphate geopolymer hollow sphere structures (FPGHSS) were prepared by the pre-bonding and curing technology. Moreover, the interface microstructure and its role on the compressive behavior were studied. The compressive properties of FPGHSS demonstrated a typical character of cellular materials, with three well defined stages in stress–strain curve. The compressive strength was approximately 5.8 MPa, and the failure of FPGHSS was mainly due to the evolution of the multi-collapsed layers of fly ashes and large macro-cracks during the compression. The microstructure of fly ash was composed of aluminosilicate glass phase, crystalline quartz and mullite. The phosphate geopolymer comprised of aluminum-phosphate phase and α-Al2O3, and the nano-pore structure was observed. Moreover, the chemical reaction interface of FPGHSS was generated. It should be noted that the horizontal cracks were mainly produced in fly ashes, and the evolution of horizontal cracks leaded to the clasped layers. Moreover, the large macro-cracks propagated preferentially in the phosphate geopolymer and along the interface region of FPGHSS, due to the dense glass phase of fly ash and the chemical reaction interface. Further, the interface structure between α-Al2O3 and amorphous phase could increase the propagation path of cracks in phosphate geopolymer.

•A two-stage transformation behavior was observed when the value of prestrain was higher than 4%.•Two kinds of martensite formed: stress-induced martensite and preferentially oriented martensite.•The martensite re-orientated and variety of crystal defects formed with the increases of prestrain.•The martensite fraction remaining in the fibers increased with the prestrain level increasing.The effect of tensile deformation on the phase transformation behaviors of TiNi fibers which were embedded in a pure aluminum matrix was discussed in this paper. Differential scanning calorimeter (DSC) was used to study the martensite transformation. The microstructures of the TiNi fiber before and after tensile deformation were observed by transmission electron microscopy (TEM). Results show that martensite induced by stress preferentially nucleated at the grain boundary and the dislocation. When the amount of tensile deformation was higher than 4%, a two-stage transformation behavior was observed in the heating process. The peak appeared at low temperature correspond to the martensite induced by stress. While the peak appeared at high temperature correspond to preferentially oriented martensite. However, the martensite fraction remaining in the fibers increased with the prestrain level increasing because part of the martensite was deformed into fully detwinned preferentially oriented martensite, which cannot be detected by DSC.

•Hollow sphere structures are tailored to broadband sound absorption.•Ceramic hollow sphere structures are prepared by pre-bonding and curing process.•Ceramic hollow sphere structures show open pore size effects on sound absorption.•Sound absorption mechanisms of CHSS are studied based on Pride–Allard model.Porous structure with micro-sized open cell was tailored for the sound absorption, and ceramic hollow sphere structures (CHSS) were prepared by low temperature pre-bonding and curing process. Micro-sized open cells of CHSS, which demonstrated normal/bimodal distribution, were mainly observed in the interstitial gaps of fly ashes. The CHSS with micro-sized open cells demonstrated a broadband sound absorption above 500 Hz, and its acoustics behavior was affected significantly by the porous structure. The calculated values of sound absorption based on the Pride–Allard model demonstrated similar trends as experimental results with the increase of frequency.

•Gd element segregated on the surface of SiC particles as well as the carbon fibers.•The Gd element reacted with the SiC particles and forms GdC2 on the surface.•The precipitation forming on the carbon fibers were concluded to be nano-scaled Gd2O3.•The interface layers on the Cf in the hybrid reinforced composite was much thinner.In present work, Cf/Mg-8Gd and SiC+Cf/Mg-8Gd composites were fabricated by squeeze infiltration method. Gd2O3 coating layers were found on the surface of the carbon fibers in these two kinds of the composites, while GdC2 precipitations were found in the hybrid reinforced composite only. Owing to this phenomenon, the coating layer in SiC+Cf/Mg-8Gd composite (88 nm) was much thinner than the one without the SiC particles (160 nm). The Gd2O3 coating layer formed on the surface of carbon fibers can improve the wettability between carbon fibers and magnesium alloy.

•Nano-crystallinity was observed in the Al matrix after impact.•The plastic deformation in B4C particle was observed after impact.•The crystal boundary in B4C particle was the type of high-angle.In the present work, B4C/2024Al composites with volume fraction of 45% were prepared by a pressure infiltration method. The microstructure of the crater bottom of B4C/2024Al composite after impact was characterized by transmission electron microscope (TEM), which indicated that recovery and dynamic recrystallization generated in Al matrix, and the grain size distribution was about from dozens of nanometer to 200 nm. Furthermore, the plastic deformation was observed in B4C ceramic, which led to the transformation from monocrystal to polycrystal ceramic grains. The boundary observed in this work was high-angle grain boundary and the two grains at the boundary had an orientation difference of 30°.

Ni layers were deposited on the two sides of pure Fe substrate by using electroplating to form Ni/Fe/Ni diffusion couple. After diffusion heat treatment, Fe–Ni laminated composite was obtained with Fe–Ni alloy/Fe/Fe–Ni alloy structure. The results indicate that the Fe–Ni layers combine well with the substrate and the Fe–Ni/Fe interface presents an interlocking microstructure with small-size grains. The concentration of element Ni in the Fe–Ni layer decreases from surface to interior exhibiting a gradient distribution. Geomagnetic shielding factor (SF) of Fe–Ni laminated composite can reach as high as 22.6, which is about seven times of that of pure Fe substrate. Mathematical equation of SF for laminated structure was derived according to magnetic circuit and resistance theory. The theoretical expression reveals that parameters such as the thickness and magnetic permeability of the shield material play an important role in the magnetic shielding behavior and the theoretical calculation results of SF coincide well with our experimental values.

•55 vol.% TiB2/2024Al composites are fabricated by pressure infiltration method.•Effect of surface roughness on tribological properties are investigated.•Optimal roughness is determined by combining microstructure and wear mechanism.55 vol.% TiB2/2024Al composites were fabricated by pressure infiltration method. The effect of surface roughness of GCr15 steel disc (Ra 0.606, 0.372, 0.023, 0.005 μm) on the tribological properties of composites was investigated. Results showed that with the change of surface roughness, there is an optimal value (Ra 0.023 μm) under which the friction coefficient and wear rate is the lowest. The optimal surface roughness is in the same order of mixture of TiO2 and B2O3, observed on the surface of TiB2 particles after pre-heating process. During sliding, the filling of this oxidation layer into the asperity gap of GCr15 and greatly reduces adhesion between aluminium and GCr15, furthermore, decreases the friction coefficient and wear rate.

•Nanostructured matrix in high volume fraction of SiCp/Al composites was achieved.•Nanostructured matrix was achieved by adding nucleating elements Sc and Zr.•The formation mechanism of nanostructured matrix was preliminarily indicated.•The nanostructured composites showed an improvement of 300% in maximum strain.High ductility and increased strength of SiCp/Al composites are highly desirable for their applications in complicated components. However, high ductility and high strength are mutually exclusive in high volume fraction SiCp/Al composites. Here, we report a novel nanostructuring strategy that achieves SiCp/Al–Sc–Zr composites with superior maximum tensile strain and enhanced tensile strength. The new strategy is based on combination of grain refinement down to ultra-fine scale with nanometric particles inside the grain through adding distinctive elements (Sc, Zr) and refining nucleation centers to nanoscale under the action of high volume fraction reinforcement during the fabrication process. The nanostructured SiCp/Al–Sc–Zr composites had an increase of ∼300% in maximum tensile strain and a 21% increase in tensile strength. This thought provides a new sight into enhancement of both strength and ductility of particle reinforcement metal matrix composites.

20 vol% TiNif/Al composite was fabricated by a pressure infiltration process. The effects of pre-oxidation of TiNi fibers on the interfacial and mechanical property of the composite were studied. As to avert severe interfacial reaction between the TiNi fiber and Al matrix, a dense oxide layer was formed on the surface of the TiNi fiber after it was oxidized in air for different time durations. Transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS) were used to study the interface of the composite. It was found that the TiO2 phase was the main component of the oxide layer. With increase in oxidation time, the thickness of the interfacial layers between TiNi fiber and Al matrix increased, and the tensile strength and elongation of the composite decreased. When the oxidation time was 1 h, the tensile strength of the composite was very close to the theoretical value of 272 MPa. Moreover, the interfacial layer can be divided into three parts: Ti–O layer next to the Al matrix, thin middle layer containing Ti element and the Ti–Ni layer next to the TiNi fiber.

An unidirectional ultra-high modulus M40J carbon fiber reinforced 5A06 aluminum alloy with volume fraction of 55% was fabricated by the pressure infiltration method. The effect of thermal cycling (−70 to 120 °C and −196 to 120 °C) on the mechanical properties of Cf/Al composites was investigated. Bending modulus increased abruptly after five thermal cycles and then reached a platform. However, after 50 cycles, the bending modulus decreased with the increase of cycles due to generation and propagation of microcracks at C fiber/Al interface. The bending strength of composites showed fluctuations between 800 and 1000 MPa, and the amount and length of pull-out fiber increased with the increase of the thermal cycling times regardless of temperature difference. Microstructure observation revealed the formation of microcracks and interface debonding at the C fiber/Al interface after thermal cycling treatment, and the amount of the microcracks and interface debonding increased with the temperature difference. The main interfacial products in annealed Cf/Al composites were rod-like Al3Mg2 and bulky Al58Mg42, and no significant Al4C3 was observed at C fiber/Al interface. The thermal cycling treatment used in the present work had little effect on the interface microstructure of Cf/Al composites. Very few dislocations were observed in the Al matrix of annealed Cf/Al composites. However, the amount of dislocations in the Al matrix increased gradually with the increase of thermal cycles. Moreover, the amount of dislocations would decrease after a certain thermal cycles due to movement and annihilation of unlike-sign dislocations.

Residual microstructure associated with the crater in 15% Ti–6Al–4V wire mesh reinforced 5A06 alloy (TC4m/5A06) composite thin target impacted by Al projectile with the speed of 2.5 km/s were investigated. The depth and diameter of crater impacted by Al projectile with the diameter of 1.6 mm are 1.62 mm and 2.8 mm, respectively. At the back face, bulge with height of 0.5 mm is produced along the impact direction and cross-shaped cracks and spalling form at the top of the bulge. With projectile diameter increasing to 2 mm, composite gets perforated and the diameter of perforation becomes 3.2 mm. Microstructured observation of crater impacted by Al projectile with the diameter of 1.6 mm shows that in the region near the pithead and around the center of crater, decohesion occurs at the interface between TC4 wire and Al matrix and the direction of decohesion is in agreement with the outline of crater. In the region at the bottom of the crater, there appears an adiabatic shear band (ASB) in a TC4 wire and two sections of wire slide with each other along the direction of ASB with a distance of 200 μm. TEM observation reveals that block-shaped Ti2Al phase with size up to 1 μm forms in the ASB at the bottom of the crater after high speed impact. Besides, amorphous structure, nanograins and ultrafine grains are found in Al matrix at the bottom of the crater.Highlights► At the back face of crater, bulge and cross-shaped cracks and spalling are formed. ► Near the pithead or middle of crater, decohesion occurs at the TC4–Al interface. ► At the bottom of crater, there appears an ASB in a TC4 fiber. ► Block-shaped Ti2Al phase forms in the ASB at the bottom of crater after impact. ► Amorphous structure and nanograins are found in Al matrix at the bottom of crater.

The in situ reaction procedure and microstructure evolution of a graphite fiber reinforced Ti-Al composite (Grf/Ti-Al) was investigated, and the stability of TiAl3 at high temperature was discussed. As-cast material was prepared by pressing molten pure aluminum into a preform, which was composed of titanium particles and graphite fibers. The in situ reaction procedure of the as-cast material was investigated by differential scanning calorimetry (DSC), and phases in the products were detected by X-ray diffraction (XRD). Experimental results showed that TiAl3 was formed first. With an increase in temperature, TiC and Al4C3 were observed, but TiAl3 decreased. In the final product, Al2O3 and TiO2 were observed. It was considered that the previous forming TiAl3 decomposed, then TiC precipitated, and subsequently, oxidation resulted in the formation of Al2O3 and TiO2.

Graphite fiber and Ti particle-reinforced aluminum matrix composite were produced by squeeze casting technology. A small amount of needle aluminum carbide at graphite fiber and Al interface was observed, and TiAl3 intermetallic compound at Ti particle and Al interface was detected. Tensile strength and bending strength of the composite have been measured. The fracture surface of the composite after tensile and bending tests was observed; graphite fiber-reinforced Al was brittle fracture, whereas Ti particle-reinforced Al was ductile fracture. The corresponding fracture mechanism was discussed.

This study is concerned with investigation of forming Ti fiber reinforced TiAl3 composite by infiltration-in situ reaction. The as-cast material was obtained by pressing molten pure Al into a preform which was composed of Ti particles and Ti fibers. Based on the differential scanning calorimetry (DSC) result, in situ reaction samples were obtained by heating as-cast materials to 660, 950, and 1300 °C, and held for 1 h, respectively. The microstructure evolution of in situ reaction samples was analyzed by scanning electron microscope and Energy dispersive X-ray (EDX). In addition, the phase composition of products was inspected by X-ray diffraction (XRD). Experiment results show that TiAl3 was formed initially, which was the unique product between Ti and Al. While at high temperature, products of Ti fibers and Al were complex, and TixAl1−x (0.25 < x < 0.75) compounds were formed around Ti fibers. Finally, TiAl3 decomposed, and oxidation occurred. The mechanism of in situ reaction between Ti and Al in this system was discussed.

Fully dense Y2Mo3O12/Al composites were prepared by squeeze-casting. Relatively mild conditions of 750 °C/20 min/50 MPa were used in order to avoid reaction of the components. SEM, Raman spectroscopy, XRD and dilatometry were used to characterize the microstructures and morphologies of the composites. Zero thermal expansion was achieved in the temperature range where the thermal mismatch strain was zero. We show that the CTE mismatch of Al and Y2Mo3O12 results in compressive and tensile strains that distort the Y2Mo3O12 lattice. We establish a novel method to measure the negative thermal expansion (NTE) materials' CTE under strain by measuring the composites' CTE and calculating the thermal mismatch strain between the NTE ceramic and the metal matrix. The relationship between thermal strain and Raman shift is established and measured and the simulated results are in good agreement. We also find Y2Mo3O12 to have a positive CTE when the surface strain is ≥0.80 × 10−2%.