P-Cr-Ti复合变质Al-25%Si合金时Cr-Ti作用机理  

Modification Mechanism of Cr and Ti in Al-25%Si Alloy Modified by P-Cr-Ti

作　　者：陈淑英[1] 刘学[1] 岳旭东[1] 常国威[1] 

机构地区：[1]辽宁工业大学,辽宁锦州121001

出　　处：《稀有金属材料与工程》2017年第4期1003-1007,共5页Rare Metal Materials and Engineering

基　　金：辽宁省高等学校杰出青年学者成长计划(LJQ2014062);国家自然科学基金青年基金(51204092)

摘　　要：采用P-Cr-Ti复合变质处理Al-25%Si(质量分数)合金,重点研究了凝固组织的变化以及Cr、Ti元素的作用机理。结果表明:与单一的P变质相比,经P-Cr-Ti复合变质后,Al-25%Si合金凝固组织中初生Si的尺寸减小了12.2%~51.7%,并且初生Si分布的均匀程度增加。Al-25%Si合金中Cr、Ti主要以TiAl_3、Ti_7Al_5Si_(12)、Al_7Cr、Al_(13)Cr_4Si_4化合物的形式存在,同时有少量的P分布在含Ti化合物中。含Ti化合物呈长条状、短杆状;含Cr化合物呈菊花状、网状,分布在初生Si之间。含Cr、Ti化合物的数量随冷却速度的增加而增加。变质处理时Al-6.5%Ti合金带入的TiAl_3相,具有使初生Si持续析出和细化初生Si的作用,但细化能力有限。凝固过程中初生Si周围形成的含Cr化合物和αCr阻止初生Si的长大与聚集,促使增加初生Si分布均匀程度。Al-25% Si alloy was treated by compound modification of P-Cr-Ti. Then the solidification microstructure and the effects of Cr and Ti elements were investigated. The results indicate that the primary Si size decreases by 12.2%-51.7% in the solidification microstructure of Al-25%Si alloy modified by the P-Cr-Ti compared with that of simple phosphorus modification, and the primary Si is more uniform. The Cr and Ti elements in the Al-25%Si alloy mainly appear as compounds including TiAl3, Ti7A15Si12, Al7Cr and Al13Cr4Si4, and there is a small amount of P in the Ti-containing compounds. Ti-containing compounds appear as long strip shapes and short rod shapes. Cr-containing compounds, which distribute among the primary Si, appear as daisy-like shapes and net shapes. The compounds containing Cr and Ti are increased in number with the increase of the cooling rate. The TiAl3 phases initiated by Al-6.5%Ti alloy make the primary Si precipitate continuously and refine the primary Si with a limited refining ability. Cr-containing compounds and act formed around the primary Si prevent the growth and gathering of the primary Si during the solidification, which leads to more uniform distribution of the primary Si.

关 键 词：Al-25%Si合金 P-Cr-Ti复合变质 元素作用机理 凝固过程 

分 类 号：TG292[金属学及工艺—铸造]