Effects Of High Mechanical Pressure And Minor TI On The Solidification Of The Zn-Al Alloys

In this paper, the solidification characteristics of the ZA27 and ZA41 binary alloys under high pressures and minor Ti was investigated in order to understand the influence of high pressure and Ti on the structure and properties of the Zn-Al alloy, which is very useful for the application of the Zn-Al alloy.Experimental results show that the macrostructures of ZA27 alloy solidified under high pressure have changed greatly. The net-like macrostructures with very fine and"+"like dendrites and directional secondary dendrites were obtained for ZA27 alloy solidified under high pressures. The higher the pressures were, the more changes had been found. Rich phase was enhanced. The melting point and solid solubility of ZA27 alloy was enhanced and the eutectic point was moved toward the Al-rich direction because of the high pressure. The high pressure benefited the nucleation of the crystalline phases and impeded their growth. The mechanical properties could be increased significantly; particularly the hardness of ZA27 alloy has been increased greatly.The structures of the ZA41 alloy solidified under high pressure were investigated. Under high pressure, the final solidified microstructure was consisted of the fine crystals with different shapes, some like the section of the cell crystals. The supersaturated a solid solution was formed and the dendritic segregation was decreased when the ZA41 alloy solidified under high pressure.As far as the Ti addition is individually concerned, the refinement result of the ZA41 alloy with 0.1% Ti addition is comparatively best. The coarse dendrite microstructure of the ZA41 alloy is refined and transformed to the uniform and small floccus microstructure, the eutectics among the grain boundaries also become finer. The tensile strength of the alloy is up to 438.23MPa, and the hardness of the alloy is up to 146.3HB, while the elongation of the alloy is 1.61%.