P-Cr-Ti复合变质Al-25%Si合金时Cr-Ti作用机理

发布时间：2018-06-01 13:44

本文选题：Al-%Si合金 + P-Cr-Ti复合变质　；参考：《稀有金属材料与工程》2017年04期

【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。
[Abstract]:Al-25Si alloy (mass fraction) was modified by P-Cr-Ti composite modification. The changes of solidification microstructure and the mechanism of the action of Cr-Ti were studied. The results show that compared with single P modification, the size of primary Si in Al-25Si alloy modified by P-Cr-Ti decreases by 12.2Cr-1. 7, and the homogeneity of primary Si distribution in Al-25Si alloy increases. The primary Si distribution in Al-25Si alloy is mainly in the form of TiAl3Ti7Al7Al5Si5Si5Si5Si5Si alloy. At the same time, a small amount of P was distributed in Ti-containing compounds. The Ti-containing compounds are long, short rods, and Cr-containing compounds are chrysanthemum, reticulate, distributed between primary Si. The amount of Cr-Ti compounds increases with the increase of cooling rate. The TiAl_3 phase brought in by Al-6.5%Ti alloy during modification has the function of continuously precipitating primary Si and refining primary Si, but the refining ability is limited. Cr-containing compounds and 伪 -Cr formed around primary Si during solidification process prevent the growth and aggregation of primary Si, and promote the homogeneity of primary Si distribution.
【作者单位】：辽宁工业大学;
【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)
【分类号】：TG292

【相似文献】