The permanent magnetic nanocomposite PrNdFeB/Fe7Co3 ribbons were prepared by directly quenching, and the microstructure and magnetic influence of composite materials with Co substitution were studied. The phase identification and the magnetic properties were measured by X-ray diffraction (XRD) and vibrating sample magnetometry (VSM). Microstructure observation was performed using scanning electron microscopy (SEM). The crystallization temperatures of the hard magnetic phase and the soft magnetic phase were measured using differential scanning calorimetry (DSC). The experimental results showed that Co addition improved the Curie temperature of magnets. When the ribbons were melt-spun at 35 m/s, the added content of Co was 4 at.%, and the magnetic properties were the best, which were remanence (Br) of 0.379 T, coercivity (Hci) of 344.4 kA/m, the maximum magnetic energy product (BH)max of 32.6 kJ/m3. Besides, the activation energy of each phase was calculated by Kissinger equation, which was 310.4 kJ/mol of Fe7Co3 phase and 510.2 kJ/mol of 2:14:1 phase, respectively.Curie temperature of melt-spun ribbons with the different content of Co elementDownload high-res image (58KB)Download full-size image

The in situ Ti5Si3/Ti inoculants were successfully prepared by vacuum arc-melting and melt-spinning method. An efficient route by adding a small quantity of Ti5Si3/Ti inoculants to Ti melt has been first proposed to modify the coarse grains of as cast microstructure of pure titanium in this paper. It was found that the microstructure of ribbon inoculants was cellular structure that composed of Ti5Si3 and α-Ti phases. The grain refining effect of the inoculants was significantly improved with the adding ratio range from 0.2% to 0.5% in weight. With the increase of addition amount of inoculants on Ti melt, the tensile strength, yield strength and microhardness of pure titanium are significantly improved except elongation. The excellent grain refining effect can be attributed to the heterogeneous nucleation of the titanium grain on the precipitated Ti5Si3 phases in the Si-rich regions and the constitutional supercooling of Si in the Si-poverty regions. It is suggested that the in situ Ti5Si3/Ti inoculants is a promising inoculants for titanium alloys.

•Rare earth element Dy is added into the Sm-Co/Fe-Co nanowires for the first time in this paper.•The addition of Dy element produces a new Fe23Dy6 phase in the nanowires and improves the magnetic properties of nanowires obviously.•The effect of different of Dy ion concentration on nanowires' magnetic properties is researched in this paper.The Sm-Co/Fe-Co and Sm-Co/Fe-Co-Dy nanowire arrays with smaller diameter are prepared by electrochemical deposition on the anodic aluminum oxide (AAO) templates in this paper. The crystal structure and magnetic properties of nanowires are characterized and analyzed. It is found that the Sm-Co nanowires change from amorphous phase to nanocrystalline state with hard magnetic characterization through annealing at 660 °C for 3 h. In this experiment, rare earth element Dy is added to the Fe-Co solution, and the three alloy nanowires are prepared and researched for the first time. The addition of Dy element produces a new Fe23Dy6 phase in the nanowires. The magnetic hysteresis loops illustrate that the magnetic properties of as-deposited nanowires is improved dramatically after heat treatment and the direction parallel to the nanowire arrays is the easy direction of magnetization which leads to nanowires possessing obvious shape anisotropy. The effect of different Dy ion concentration on nanowires' magnetic properties is investigated in this paper.

Vacuum rapid solidification technique was utilized to prepare TiB+TiN/Ti inoculants ribbons, which were added to TC4 alloy melt to get refined titanium matrix composites (TMCs). For comparing and analyzing the influence of inoculants, authors mainly studied microstructure and mechanical properties of TC4 alloy modified and reinforced by TiB+TiN/Ti inoculants ribbons prepared by in situ reaction. The in situ reaction are: (1) 3Ti+2BN→TiB2+2TiN, (2) Ti+TiB2→2TiB. Microstructure and morphology observation showed that the grain size of TMCs was refined as the volume fraction of reinforcements increased. It is worth noticing that the reinforcements in the TMCs prepared by inoculating method tend to distributed in matrix homogeneously. The tensile test results showed that the tensile strength of TMCs increased significantly by inoculating. Inoculating method showed advantages to preparing by in situ reaction directly. The hardness and wear-resisting property of TMCs were also investigated and found to be promoted as reinforcements content increased.

In the experiment, Ti75Zr11Si9Fe5 and Ti66Zr11Si15Fe5Mo3 ingots were prepared by vacuum arc-melting furnace. Both Ti alloy ribbons of 3–5 mm in width and about 80 μm in thickness were made from bulk samples by an as-quenched technique under an argon atmosphere. Both melt-spun glassy ribbons exhibit large supercooled liquid regions, high reduced glass transition temperatures, and good thermal stabilities. For both alloys, the stable phases after heating are a Ti glassy matrix and in situ nano-Ti5Si3 particles encircled by nano shell of β-Ti. After the Ti5Si3/β-Ti nano-core–shell structure was in situ formed, in situ Ti5Si3/β-Ti nano-core–shell structure toughened glassy Ti alloy matrix composites were prepared. For the Ti66Zr11Si15Fe5Mo3 ribbons, its high strength is attributed to both Mo solution strengthening and nano core–shell Ti5Si3/β-Ti toughening and dispersion strengthening. Observations and analysis on microstructure and fracture morphology of melt-spun glassy ribbons indicated that multi-slip bands were formed during the tensile test.

•Rock candy particles were used as space-holders to prepare open-celled porous Cu.•A relaxational internal friction peak was found at around 260 °C.•The porous Cu has a significantly enhanced damping capacity compared with the solid Cu.•Mechanisms of the internal friction peak and damping enhancement were discussed.An open-celled porous Cu has been successfully prepared by using rock candy particles as space-holders. Resultant material exhibits uniformly distributed and interconnected pores. Results of damping test show that a relaxational internal friction peak arises at around 260 °C. Corresponding to the appearance of this peak the storage modulus has a softening valley. This peak has been ascribed to the sliding of grain boundaries under the applied stresses during damping test. It is also found that compared with the solid Cu, the damping capacity of the porous Cu has been significantly enhanced due to the effect of pores and the micro-plastic deformation in the Cu matrix.

•CeB6/Al ribbon as aluminum alloy inoculant was prepared by melt-spinning.•Grains of Al were significantly decreased with 0.4% CeB6/Al ribbon.•Mechanical properties of Al have been improved by addition of CeB6/Al ribbon.•CeB6/Al interface is smooth and clean.The CeB6/Al inoculant with variable sizes of CeB6 particles were prepared by arc-melting and controlled by melt-spinning and then verified the refining efficacy in pure aluminum. It was found that the grain refining efficacy can be significantly improved by controlling the CeB6 particle size. The pure aluminum can be refined from a grain size grade of 870 ± 25 μm to 150 ± 35 μm by addition of CeB6/Al ribbon with a very small ratio of 0.4% in weight. Thereafter, the mechanical properties of the pure aluminum, including the tensile strength, yield strength and microhardness, were obviously improved by the addition of the CeB6/Al ribbon. The excellent grain refining can be attributed to the nano-sized refiner particles and the well-banded particle/matrix interface which are benefit for the nucleation of aluminum during solidification. It is suggested that the CeB6/Al inoculant ribbon is a promising inoculants for aluminum alloy.

•Hydroxyapatite (HA) powders were added to the electrolyte.•The HA powders have participated in the formation reactions of MAO coating.•The growth efficiency of MAO coating was greatly enhanced owing to the HA addition.•The specimen anodized in the HA-containing electrolyte has a better corrosion resistance.•The specimen anodized in the HA-containing electrolyte can more efficiently induce Ca–P precipitation.To improve the corrosion resistance of magnesium, micro-arc oxidation (MAO) coatings were prepared on magnesium substrates in an aqueous solution with and without hydroxyapatite (HA) powders addition. The micrographs of scanning electron microscopy (SEM), the energy dispersive spectrometer (EDS) spectra, and X-ray diffraction (XRD) analysis show that the HA powders added into the electrolyte have participated in the formation reactions of MAO coating and the growth efficiency of MAO coating is greatly enhanced. Potentiodynamic polarization tests and immersion tests in simulated body fluid (SBF) confirm that the specimen anodized in the HA-containing electrolyte has a better corrosion resistance than the specimen anodized in the HA-free electrolyte. Immersion tests also indicate that the specimen anodized in the HA-containing electrolyte can more efficiently induce Ca–P precipitation compared with the specimen anodized in the HA-free electrolyte.

•Different potassium titanates have different behaviors in simulated body fluid.•Low potassium titanate may transform into calcium titanate in body fluid environment.•Potassium hexatitanate possesses excellent stability biocompatibility.Two sintering products containing potassium titanates were fabricated and cultivated in simulated body fluid for 12 days. It was found that the molar ratio of titanium/potassium of potassium titanate is a key factor to control the behavior of potassium titanate in body fluid environment. Low potassium titanates such as K2Ti2O5 and K2Ti4O9 transformed into calcium titanate due to its intrinsic characteristics of ion exchange. However, potassium hexatitanate was structurally stable adsorbing needle-like hydroxyapatite. The experimental results indicated that potassium hexatitanate possesses excellent biocompatibility which is better than low potassium titanates.

The novel Al-5Ti-1B-1RE nanoribbons were synthesized by melt-spinning. The microstructure showed that the Al-5Ti-1B-1RE nanoribbon consisted of granular-like TiB2 and core-shell-like TiAl3/Ti2Al20Ce. The Al-5Ti-1B-1RE nanoribbon could give rise to the excellent refining effect on as-cast A356 alloys. The refining efficiency and formation mechanism of Al-5Ti-1B-1RE nanoribbons were investigated. In accordance with the experimental results, it could be seen that the Al-5Ti-1B-1RE nanoribbon could maintain the refining effect after 60 min of holding. Additionally, owing to the addition of Al-5Ti-1B-1RE nanoribbon, the mechanical properties of A356 alloys could be enhanced significantly.XRD patterns of different alloys (1) Alloy 1; (2) Alloy 2; (3) Alloy 3

Metal–matrix composites reinforced with sub-micrometre particles of TiC and AlN are made by in situ reaction of CH4 and NH3 gases with an Al–6.2Ti–4.6Mg (wt.%) melt, with a range of processing conditions being explored. High-resolution electron microscopy of the particle/matrix interfaces show that in all cases they are clean and well bonded. The orientation relationships between the various types of particle and the matrix are examined. In samples where the Ti is completely consumed by the reaction, the TiC particles are coated with a thin layer of Al3Ti. The presence of this layer has little effect on the mechanical properties of the composites.

The novel Al–Ti–B–Re nanorefiners have been prepared by melt-spinning. The microstructure observation of the melt-spun Al–Ti–B–Re grain refiner shows that it consists of granular-like TiB2 and core–shell-like TiAl3/Ti2Al20Ce. The formation mechanism and microstructure of core–shell-like TiAl3/Ti2Al20Ce in melt-spun Al–Ti–B–Re grain refiner were investigated systematically in this paper.Highlights► The novel Al–Ti–B–Re nano-refiners have been prepared by melt-spinning. ► The melt-spunAl–Ti–B–Re grain refiner is much finer than that in refiner rod. ► A mathematical model cab be established to determine the conversion rate of Ti2Al20Ce shell.

Titanium alloy with a low density, high specific strength, corrosion resistance and good process performance, is the ideal structural materials for the aerospace engineering. Based on the microstructure of titanium alloys, it can be divided into α-type titanium alloys (heat-resistant titanium alloys), β-type titanium alloys and α + β-type titanium alloys. The research scopes also include the fabrication technology of titanium alloys, powder metallurgy, rapid solidification technology, and other military and civilian applications of titanium alloys. Titanium and its alloys have become the ideal structural materials used for the fuselage, and accounted for a significant part of the structural quality in most military aircrafts. Titanium’s future market expectations need to be considered in the macro level market. Apart from the supply and demand trends of titanium market, it is necessary to consider the impact of technological innovations that can help to reduce the cost of titanium production.

Ti-based alloy Ti64Zr5Fe6Si17Mo6Nb2 (At %) and Ti70Zr6Fe7Si17 (At %) ribbons with a width of 3–5 mm and thickness of about 80 um were fabricated by a single roller spun-melt technique. The feature of the alloy composition satisfies the three empirical rules. Amorphous structures of both alloys were confirmed by the X-ray diffraction pattern. To test the biocompatibility, both alloys were cultivated in the simulate body fluid (SBF). After 15 days, the Ca phosphates depositions on alloys surfaces were gained. Moreover, n(Ca)/n(P) atom ratio of the deposition is about 1.6/1, which approaches to that of human bone—1.66/1, suggesting that both alloys were with a favorable biocompatibility.

Fe3Co7 alloy nanowire arrays have been fabricated by direct current electrodeposition of Fe2+ and Co2+ into anodic aluminum oxide (AAO) templates. The phase structure and magnetic properties of the nanowires were studied by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), and vibrating sample magnetometer (VSM). Magnetic measurements show that the coercivity and remanence of the as-deposited Fe3Co7 Alloy nanowires increase dramatically after heat-treatment at 773 K for 2 h, and the nanowire arrays exhibit uniaxial magnetic anisotropy with easy magnetization direction along the nanowire axes owing to the large shape anisotropy. The great difference between practical coercivity and ideal coercivity was also discussed in detail.

Ti-based amorphous alloys Ti70Zr6Fe7Si17 (at.%) and Ti64Zr5Fe6Si17Mo6Nb2 (at.%) are fabricated by a single roller spun-melt technique. The feature of the alloy composition satisfies Inoue’s three empirical rules. Amorphous structures of the both alloys were confirmed by the X-ray diffraction patterns. The both alloys were cultivated in the simulate body fluid (SBF) for 15 days and the experiment result shows that Ca phosphates depositions on alloys surfaces were gained. Moreover, n(Ca)/n(P) atom ratio of the deposition is about 1.6/1, which approach to that of human bone – 1.66/1, suggesting that the both alloys were with an excellent biocompatibility.

The influence of rapid solidification of Cu-P intermediate alloy on the wear resistance of Al-Si alloy is studied. TEM analysis indicates that at the cooling speed of 105-106 °C/s, the microstructure of melt-spin Cu-P ribbon consists of nano-grains and a little amount of amorphous areas, and the grain size of Cu3P in Cu-P intermediate alloy is decreased from 5-40 μm to 30-50 nm. Results show that the wear resistance of Al-Si alloy modified by melt-spin intermediate alloy are better than that of Al-Si alloy modified by massive ones; wear rate is decreased from 0.86% to 0.39%. Therefore, melt-spin treatment of Cu-P intermediate alloy is effective to improve the wear resistance of Al-Si alloy.

Sm3(Fe,Ti)29Nx/α-Fe dual-phase nanometer magnetic material was fabricated through rapid solidification, crystallization and nitridation of Sm-Fe (Ti) alloy. The effect of combination of rapid solidification and Ti alloy addition on the phase formation and microstructure of the Sm-Fe alloy is investigated in this paper. The microstructure of amorphous phase and dual-phase nano-grain crystals before and after crystallization annealing were observed using a high-resolution transmission electron microscope (HREM). The dual-phase nano-grains after annealing were compacted together with a clear interface with the direct exchange-coupling mechanism. Different annealing processes were used to examine the melt-spun alloy. Comparison of the images of SEM showed that annealing at 750 °C for 10 min was most suitable to get homogeneous and nano-grains. No obvious kink was detected in the second quadrant of the hysteresis loop like a single hard magnet, and strong exchange coupling was found between hard magnets and soft magnets.

Porous nanocrystalline TiO2 films have been prepared on cp-Ti substrates for biomedical usage by a sol–gel process from the solutions containing polyethylene glycol (PEG) as a template. Variations of the crystal structure with heat-treatment temperature determined by XRD are different for TiO2 films and powders, due to the effect of titanium substrate. The surface texture of porous TiO2 films is analyzed by means of SEM and found to greatly depend on the concentration and molecular weight of PEG. The pore formation mechanism is discussed in relation to the self-assembly of PEG and phase separation between PEG adsorbed on TiO2 oligomers and ethanol.

Sm2Fe16Ti1Ny powder is synthesized by HDDR treatment and nitrogenation. As-cast Sm2Fe16Ti1 alloy has a few preferred directions. The main phase of Sm3(Fe,Ti)29 and the secondary phases of SmFe11Ti, SmFe2 or Sm(Fe,Ti)2 as well as little α-Fe(Ti) coexist in as-cast alloy. In the as-homogenized ingot, the main phase Sm3(Fe,Ti)29 still co-exists with Fe9.5SmTi1.5, SmFe11Ti and a few Sm-rich phases. When Sm2Fe16Ti1 alloy is treated by different cycles of HDDR process, the Sm2(Fe,Ti)17 main phase and a little α-Fe(Ti) present. Moreover, HDDR process contributes to the cracks of powder and grain boundaries. After the powder was nitrogenated for less than 12 h, the phase compositions are not changed any more, where the content of Fe-rich phases is increasing with respect to nitrogenation time. Moreover, the diffraction peaks of Fe-rich phases are little shifted to lower angle side. The nitrogenation process mainly includes two stages, one is fast reaction and diffusion between nitrogen atoms and Sm–Fe–Ti phases, the other is long-time homogenized diffusion of nitrogen. The optimal coercivity of 1859 Oe is obtained at nitriding 6 h, and the excellent magnetization of 126.4 emu g−1 and remanence of 48.3 emu g−1 are presented at nitriding 12 h.

Sm2Fe17−xNbxNy (x = 0−4) powder was synthesized by HDDR treatment and nitrogenation. The effects of partial Nb substitution for Fe on the structural and magnetic properties of Sm2Fe17−xNbx alloys and their nitrides were investigated. It was seen that Sm2(Fe, Nb)17 phase exists in both annealed and HDDR-treated Sm2Fe17−xNbx alloys. However, its content is decreased with the increase in Nb substitution. In annealed alloys, Sm2(Fe, Nb)17 phase becomes unstable and will dissociate into SmFe2 and Fe-rich phases when x > 1.5. With HDDR-treatment, the Nb concentration in recombined Sm2(Fe, Nb)17 phase is decreased, and the content of Fe-rich phases is increased. Sm2Fe17−xNbx powder exhibits dendritic cracks and fine particles with a size of less than 300 nm. In nitrogenated alloys, N atoms mainly enter 2:17-type phase to form Sm2(Fe, Nb)17Ny. Partial Nb atoms in Sm2(Fe, Nb)17Ny phase will be released or excluded by nitrogen atoms. Fe-rich phases increase, and are followed by the amorphous Sm2(Fe, Nb)17Ny phase. Nb substitution for Fe with x = 0.5 and 1.0 in Sm2Fe17−xNbxNy powders increases the coercivity and remanence. But when x is greater than 2.0, Nb substitution will deteriorate the magnetic properties.

Using the process that titanium alloys were embedded by nanometer titanium dioxide powders and sintered in the high temperature furnace, the nano-TiO2/titanium alloys biomedical material was fabricated out. The particle size of TiO2 particles on the surface of Ti alloy was mainly 50–90 nm. The experimental results indicated that the films of nanocrystalline titanium oxide powders on the surface of Ti alloy were with an excellent biocompatibility. By cultivation in the simulated body fluid (SBF) for 7 days, the Ca phosphates were deposited on the specimen surface; and n (Ca) / n (P) atom ratio is about 1.6 : 1, which is similar to that of HA and human bone.

Highly ordered Co nanowire arrays were grown using a direct current (DC) electrodeposition method based on an anodic aluminum oxide (AAO) template. The electrolyte consists of CoSO4·7H2O and H3BO3 in distilled water. Co nanowires fabricated by electrodeposition are cylindrical monocrystals with a packed surface, and behave as hcp dominant structures. The nanowires are preferentially oriented along the [1 0 0] direction. The effective demagnetizing factors parallel and perpendicular to the plane of the film are Neff(∥)=0.65 and Neff(⊥)=0.175, respectively. The magnetic property of the Co nanowire arrays depends on the concentration of the deposition electrolyte and the deposition voltage.