摘要
合金元素Cd的添加促进了铸造Al-Si-Cu-Mg合金的时效过程,提高了合金的峰时效硬度,加快了合金的硬化速度.当加入0.27%Cd时,合金的强度提高了20%;但加入量继续增大,强度反而降低. SEM,DSC和TEM分析显示,Cd加快了亚稳相的析出,较早地形成了细小而密集的亚稳相;同时,较大的富Cd相、少量稳定相和过剩硅相质点的均匀析出,对合金起到了第二相强化的作用.在这两类析出相的共同作用下,合金获得了高的峰时效强度.但当合金中Cd的含量超过0.27%时,会形成一些富Cd的多元相和纯Cd质点,这些相的出现导致了合金机械性能的下降.
The addition of Cd promotes the age-hardening process of Al-Si-Cu-Mg alloy, increases the peak hardness and reduces the time to reach peak hardness. The UTS increases 20% when 0.27% Cd is added in, on the contrary, strength decreases if the content of Cd exceeds 0.27%. The results of SEM, DSC and TEM reveal that trace addition Cd stimulates nucleation of metastable phases and accelerates the following aging process of alloys. At the same time, some larger Cd-rich particles and stable phases formed in the matrix, which strengthen alloys as second-phase. In the combined action of those two kinds of precipitates, the peak strength of alloy improves remarkably. However, when the content of Cd exceeds 0.27% some Cd-rich phases and pure Cd particles form, and those particles soften grain boundary and result in the decrease of alloy strength.
出处
《金属学报》
SCIE
EI
CAS
CSCD
北大核心
2004年第8期867-872,共6页
Acta Metallurgica Sinica
基金
国家自然科学基金资助项目 50275098