论文部分内容阅读
采用金相显微镜、扫描电镜、硬度计等测试手段,研究了La对A356合金的组织和硬度的影响。结果表明,稀土La对α-Al相的细化和Si相的变质都起到明显作用。随着La含量的增高,晶粒逐渐变小,加入0.4%La,α-Al相达到最小,但随着La含量的增高,在晶界处形成的Al Si La型结晶相也随之增多,La含量达到0.4时,结晶相大量聚集,形成粗大的块状相,对组织起破坏作用;加入0.2%La时,共晶Si相呈细小颗粒状,继续增加La含量到0.4%,变质作用减弱;加入0.3%La时,Si相硬度达到最高(61.4HB)。
The effects of La on the microstructure and hardness of A356 alloy were investigated by means of optical microscope, scanning electron microscope and hardness tester. The results show that rare earth La has a significant effect on the refinement of α-Al phase and the deterioration of Si phase. With the increase of La content, the grain size becomes smaller and the content of α-Al phase reaches the minimum when 0.4% La is added. However, with the increase of La content, the crystalline phase of Al Si La formed at the grain boundary also increases, When the content of La reaches 0.4, the crystalline phase accumulates in a large amount to form a coarse massive phase, which destroys the structure. When 0.2% La is added, the eutectic Si phase is fine and granular, and the La content is further increased to 0.4% When 0.3% La was added, the hardness of Si phase reached the highest (61.4HB).