Continuous Al2O3 ceramic fiber reinforced Ti/Al3Ti metal-intermetallic laminated (CCFR-MIL) composite was fabricated using a vacuum hot pressing (VHP) sintering method and followed by hot isostatic pressing (HIP). The microstructure characteristics of the interfaces between Ti and Al3Ti, as well as Al2O3 fiber and Al3Ti intermetallic were analyzed by scanning electron microscopy (SEM). Elemental distribution in the interfacial reaction zones were quantitatively examined by energy-dispersive spectroscopy (EDS). The phases in the composite were identified by X-ray diffractometer (XRD). The mechanical properties of the CCFR-MIL composite were measured using compression and tensile tests under quasi-static strain rate. The experimental results indicated that the residual Al was found in Al3Ti intermetallic layer of CCFR-MIL composite. The interfacial reactions occurred during HIP and the reaction products were determined to be Al2Ti, TiSi2, TiO2 and Al2SiO5 phases. Compared to Ti/Al3Ti MIL composite without fiber reinforcement, both the strength and failure strain of CCFR-MIL composite under both compressive and tensile stress states increased due to the contribution of the continuous ceramic Al2O3 fiber.

The bulk titanium tri-aluminide intermetallic alloy was fabricated via foil reactive sintering using Ti and Al foils in the vacuum. Scanning electron microscopy (SEM) results demonstrated that the original Ti and Al foils were fully reacted and the only synthesized product is monolithic intermetallic Al3Ti. The basic physical properties of the fabricated intermetallic, such as Young's modulus and Poisson ratio, were determined using an ultrasonic wave measurement technique, and the compressive mechanical responses under both quasi-static and high strain rates were studied using universal load frame and modified split Hopkinson pressure bar system, respectively. The experimental results indicated that intermetallic Al3Ti exhibits brittle features, and its compressive strength was sensitive to strain rate. Moreover, the strain rate hardening behavior under high rate range is stronger than that under quasi-static deformation conditions.

•A feasible method for fabricating Ti-(SiCf/Al3Ti) laminated composite is exploited.•Formation mechanism of unique metal/(fiber-reinforced-intermetallic) laminated structure of the composite is discussed.•The composite shows good comprehensive mechanical properties.•The effect of reaction annealing on the microstructure and mechanical properties of the composite are investigated.The innovative Ti-(SiCf/Al3Ti) ceramic-fiber-reinforced metal-intermetallic-laminated (CFR-MIL) composites were successfully fabricated by vacuum hot pressing using titanium foils, aluminum foils and SiC ceramic fibers. The synthesized Ti-(SiCf/Al3Ti) composite showed a unique multilayered microstructure consisting of alternating SiCf/Al3Ti composite layers (SiC fiber as reinforcement) and Ti layers. In addition, reaction annealing technique was employed to improve the interfacial performance of SiC fiber with Al3Ti matrix. The microstructure evolution of the laminated composite during hot-pressing and annealing was experimentally characterized using scanning electron microscopy and energy dispersive spectroscopy. The formation mechanism of micro-laminated structure was discussed. Furthermore, the mechanical properties of the Ti-(SiCf/Al3Ti) laminated composite and its components were investigated by tensile and nanoindentation tests. The results indicated that Ti-(SiCf/Al3Ti) laminated composite exhibited superior mechanical properties compared to Ti-Al3Ti, which was likely attributed to the introduction of SiC fiber. The failure mechanism of CFR-MIL composite was the combined fracture behaviors of ductile fracture of Ti, brittle fracture of Al3Ti and fiber debonding, pullout and breakage of SiC.

A large diameter Hopkinson tube has been developed to measure the dynamic fracture toughness of materials. The stress wave propagation behavior in the Hopkinson tube under different impact conditions were studied both experimentally and numerically. Both the experimental and simulated results indicated that the characteristics of the incident stress pulse critically depended on the impact alignment conditions. When the striker tube impacts the incident tube in an axial, normal alignment condition, the incident pulse shows an obvious dispersive effect. While under an oblique impact condition, a smooth incident pulse with a long rise time is achieved. Therefore, an oblique impact pulse shaping technique is proposed in this study.

The tensile and compressive behaviors of an extruded Mg-8Y-1Er-2Zn alloy containing a long period stacking ordered (LPSO) phase were investigated. Compared with the tensile results, the alloy exhibits higher values of the yield stress, strain to failure and work hardening rate in compressive tests, which indicates that the alloy exhibits an asymmetry of tensile-compressive mechanical behaviors. The LPSO phase cracks during tensile deformation while it exhibits a kinking characteristic in the process of compression. It can be concluded that the two different deforming modes of the LPSO phase are the cause of the asymmetry of tensile-compressive mechanical behaviors.

A novel specimen was designed to study the interface tensile behavior and fracture mechanism of the Ti/Al3Ti Metal-Intermetallic Laminate (MIL) composite under quasi-static and high strain rates. The experimental results indicated that the interface tensile strength of the Ti/Al3Ti MIL composite increases with increasing strain rate. The fracture mechanisms of the Ti/Al3Ti MIL composite are different under quasi-static (~0.001/s) and high strain (~300/s) rates. Generally, fracture only occurs in the interface under quasi-static tensile condition, while the fracture is also found in Al3Ti layer apart from the interface under high strain rate. The quasi-cleavage features are visible in the interface surface of Ti layer in both quasi-static and high strain rates. Moreover, large dimples are found in the fracture surface under high strain rate, and the tearing ridges are more than that under quasi-static strain rate. The brittle Al3Ti layers show an intergranular fracture behavior, along with minor transgranular fractures and secondary micro-crack formed in the grain boundary.

Ti/Al3Ti metal-intermetallic laminate (MIL) composite is fabricated using Ti and Al foils through the vacuum sintering process. The fracture behavior of the MIL laminate composite under dynamic loading is investigated via modified Hopkinson bar loaded three-point bending fracture test. An experimental–numerical hybrid method is used to simulate the fracture behavior of MIL composite. In this method, the brittle damage model and plastic kinematic model are employed to represent the dynamic responses of the brittle intermetallic matrix Al3Ti and ductile reinforcement of Ti, respectively. As the boundary condition, displacement data obtained from dynamic three-point bending fracture test are imported into the finite element software package for simulation. Finite element model is validated through the comparison of the load–displacement curves from numerical simulation and the Hopkinson bar loaded three-point bending test. In addition, the dynamic damage evolution behaviors of the laminate composite, including crack deflection, delamination, plastic deformation, and brittle fracture are investigated using the post-process technique of finite element software package. The current study demonstrates that the MIL composite has excellent damage tolerance due to the multiple energy-absorbing mechanisms.

Metal-intermetallic laminate composites (MIL) based on the Ti-aluminide system are a new class of lightweight structural materials that can be used as either appliqué or structural armor. The explicit 2D finite element code LS-DYNA was employed to investigate the ballistic performance and failure mechanism of MIL composite plate subjected to impact loading. For comparison’s sake, the penetration simulation was also conducted for a monolithic intermetallic Al3Ti sample under the same conditions. Damage tolerant abilities of the two targets were evaluated based on the analysis of the projectile tail velocity, crack density and absorbed material energy. The simulation results indicated that when cracks initiated in the Al3Ti matrix propagated to the interface between the matrix and reinforcement, their directions changed due to the bridging effect of the reinforcement Ti, which enabled the MIL composite to consume more energy as a result of the increase of the crack path lengths created by the crack deflection and bifurcation. Additionally, some other energy-absorbing mechanisms, such as deflection of cracks, plastic deformation of the ductile Ti also play important roles in enhancing the energy-absorbing capacity of the MIL composites.