Mn和Si对Al-Mg-Si-Cu合金组织和性能的影响

通过拉伸实验以及扫描电镜(SEM)、能谱(EDS)和透射电镜(TEM)分析,研究了Mn和Si含量变化对新型Al-Mg-Si-Cu合金显微组织和力学性能的影响.研究结果表明,随Mn含量的增加,合金的时效硬化性降低.当添加质量分数0.35%Mn时,合金的Rm变化不大但ReL和Ae明显提高;继续增至质量分数为0.7%Mn时,强度和延伸率均下降,这是由于添加Mn同时增加了粗大夹杂相和细小弥散相的体积分数所致.随Si含量的增加,合金的时效硬化性提高,合金的Rm提高但ReL和Ae降低,时效强化相β″的析出密度增加.

Effects of Mn and Si on Microstructure and Mechanical Properties of Al-Mg-Si-Cu Alloy

Effects of Mn and Si contents on microstructure and mechanical properties of the new-type Al-Mg-Si-Cu alloy were investigated by scanning electron microscopy (SEM), energy dispersive spectrum (EDS) and transmission electron microscopy (TEM). The results showed that the age-hardenability of the alloy decreases with increasing Mn content. When adding 0.35% Mn to the alloy, the ultimate tensile strength (Rm) changes little while the yield strength (ReL) and elongation (Ae) increase significantly. When adding 0.7% Mn to the alloy, both the strength and elongation decrease because the volume fractions of both coarse insolube constituents and fine dispersoids increase simultaneously. With the Si content increases, the age-hardenability of the alloy is improved with increasing Rm and decreasing ReL and Ae especially, the density of the age-hardening phase β″ precipitates increase.