等通道转角挤压Al-26%Si合金的组织和冲击性能

Microstructure and Impact Property of Al-26%Si Alloy after Equal Channel Angular Pressing

采用等通道转角挤压工艺(ECAP)细化了Al-26%Si合金中的组织,研究了该合金在不同温度下的冲击性能及断口形貌。结果表明:ECAP能有效细化该合金的晶粒,块状初晶硅尺寸明显减小且棱角钝化,针状共晶硅呈颗粒状弥散分布于基体中,300℃下挤压16道次后合金的室温(11℃)冲击功约为铸态的5倍;低温下,挤压16道次后合金的冲击性能随温度下降变化不大;当冲击温度由室温升高至100℃时,合金的冲击性能有所下降;铸态试样的断裂机制以脆性断裂为主,挤压后试样的断裂机制以韧性断裂为主。

Equal channel angular pressing（ECAP） technology was applied to Al-26%Si alloy for refining the microstructure,the impact property and fracture morphology of the alloy were studied at different temperatures.The results show that ECAP could effectively refine grains of the alloy,decrease block primary silicon size and passivate edges.Needle-like eutectic silicon in granylar form dispersed in matrix.Room temperature impact energy of the alloy was 5 times of that of as-cast sample after pressing for 16 passes at 300 ℃.At low temperature,impact property of the alloy changed little with the decrease of temperature after pressing for 16 passes.Impact property of the alloy decreased when impact temperature raised to 100 ℃ from room temperature.The fracture mechanism of as-cast and pressed samples was mainly brittle fracture and ductile fracture respectively.