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In current study, microstructure and high-temperature mechanical properties of ZK60 magnesium alloy reinforced by SiC whiskers were investigated after casting, the KOBO extrusion and aging processes. For this purpose, ZK60/SiCwcomposite specimens were prepared by stir casting technique. In order to achieve a laminar structure and improve the strength, the samples were subjected to KOBO extrusion technique and precipitation hardening, resulting in improved strength and increased ductility. The former is due to grain refining and formation of precipitates in the microstructure, while the latter is attributed to grain refining and formation of laminar structure. To evaluate the strength of the specimens, tensile test was carried out at ambient and high temperatures. It was found that the alignment of whiskers and crystalline orientation during the KOBO extrusion process increased the anisotropic strength along with improvement of elastic modulus specially in the extrusion direction. Moreover, characterization results after the hot tensile test determined that with increasing the test temperature, yield stress, ultimate tensile strength (UTS), and elastic modulus declined nonlinearly. At last, fracture surfaces of the composite samples were investigated and it was confirmed that the applied load caused the fracture of the whiskers and, on the other side; cavity nucleation resulted in significant elongation in the specimens.

In this research, Al/Cu/Mg multilayered composites were produced by the accumulative roll bonding (ARB) process and then annealed at different temperatures and times. Microstructural studies showed that with increasing temperature and annealing time in the zero cycle samples, the thickness of the intermetallic compounds (Al3Mg2and Al12Mg17) increased. Also, optical microscopy (OM) images displayed that the Al3Mg2growth rate was higher than Al12Mg17. The effect of accumulative strain in various annealing conditions on the thickness of the intermetallic compounds is very low. Its effect is more accelerated to the nucleation of the compounds. Plus, the growth mechanism of the intermetallic layer of Al/Mg was determined to be controlled by diffusion and reaction. The activation energy of Al3Mg2and Al12Mg17were calculated to be 73 and 143 Kj.mol−1, respectively. Evaluation of the grain structure of magnesium layers showed that the grains were equiaxed and strain-free for magnesium at zero cycle and different heat treatment conditions. Besides, shear bands formed by the shear strain concentration enhanced the nucleation of magnesium grains around them in the annealing process and diminished the size of magnesium grains compared to the farther regions. Furthermore, the layer of Al3Mg2intermetallic compound with equiaxed column structure formed after annealing at different temperatures and times as well as various cycles of ARB.