热暴露对新型铝基活塞合金组织和性能的影响

研究了Al-Si-Cu-Mg-Ni新型活塞合金经过固溶时效热处理后,再在350℃热暴露不同时间(0～1 000 h)后的显微组织和性能.结果表明:随着暴露时间的延长,合金的室温和高温剩余强度明显下降,在0～10h,强度降低较快,10h后,合金的室温和高温抗拉强度基本稳定在209 MPa和51 MPa;随着暴露时间的延长,合金的伸长率明显提高,在0～1 00 h,伸长率显著提高,100 h后,其室温和高温伸长率基本稳定在2.8％和8.9％.随着热暴露时间延长,热处理组织中的块状初生硅无明显变化,粒状共晶硅长大并粗化,均匀地分布于基体中,Q和θ相长大并粗化.

Effect of Thermal Exposure on the Microstructure and Mechanical Properties of New Type Aluminum Based Piston Alloy

The microstructure and mechanical properties of the new type aluminum based piston alloy were investigated,and the heat treatment samples were subjected to thermal exposure at 350 ℃ for 0 to 1 000 h.The results show that,the room temperature and high temperature residual strength decreased obviously with the increase of the exposure time.The strength decreased rapidly at 0~10 h,the room temperature and high temperature tensile strengths were 209 MPa and 51 MPa after 10 h;the elongation increased rapidly at 0~100 h,the room temperature and high temperature elongations were 2.8% and 8.9% after 100 h.With the increase of thermal exposure time,massive primary silicon had no significant change,granular eutectic silicon grew and coarsened,the eutectic silicon uniformly distributed in the matrix,and Q and θ phases grew up and coarsened.