摘要
加入微量Sr(0.01%—0.1%,质量分数)可明显细化AZ91D镁合金晶粒,随Sr含量增加,初生相α-Mg尺寸逐渐减小,而二次枝晶间距变化不大,同时β-Mg_(17)Al_(12)析出相增多.Sr添加量为0.1%时,针状或块状Al_4Sr相依附在枝晶间的β-Mg_(17)Al_(12)相上析出.Sr在AZ91D合金凝固固-液界面前沿富集,并且优先在曲率较大的枝晶端面富集,从而抑制晶粒长大,细化了合金中初生相α-Mg;同时,Sr在枝晶的尖端富集降低了初生相α-Mg的尖端生长优势,改变了初生相形貌.
The addition of 0.01%-0.1%Sr （mass fraction） to AZ91D alloy decreased the grain size obviously and changed the morphology of the primary phase α-Mg. With the increase of Sr content the morphology ofβ-Mg17Al12 phase in the alloy was changed and its amount increased. Meanwhile, the needle-like or block-like Al4Sr phase adhering to theβ-Mg17Al12 phase distributes among interdendrities. The enrichment of Sr element at solidification interface front, especially at the tip of α-Mg dendrite, restricts the growth of α-Mg dendrite and changes the preferential growth of α-Mg, which resulted in the grain refinement and the blunting of α-Mg dendrite.
出处
《金属学报》
SCIE
EI
CAS
CSCD
北大核心
2007年第11期1171-1175,共5页
Acta Metallurgica Sinica
基金
国家自然科学基金项目50774075
国家科技支撑计划项目2006BAE04B01-4资助~~
