稀土对A6MOLY合金铸态组织及夹杂物的影响

Influence of Rare Earth on Microstructure and Inclusions of A6MOLY Cast Alloy

采用金相显微镜和QUANTA-400型环境扫描电子显微镜对添加稀土和未加稀土的A6MOLY合金铸态组织和夹杂物进行了观察,并探讨稀土的作用机理。结果表明,A6MOLY合金中添加稀土后,魏氏组织减弱,晶粒有所细化,夹杂物的尺寸减小,形状由不规则变为圆粒状,分布趋于弥散。稀土的合金化作用改善了A6MOLY合金的铸态组织。A6MOLY合金中加入稀土,形成高熔点的稀土夹杂物。由于稀土的吸附作用及稀土夹杂物的非均质晶核作用,阻止了夹杂物的进一步长大,使夹杂物变得细小圆整、弥散分布。

The microstructure and inclusions of A6MOLY cast alloy without/with rare earth were observed by metallographic microscope and QUANTA-400 environmental scanning electronic microscope, and the effect mechanism of rare earth on microstructure and inclusions was investigated. The results show that adding rare earth in A6MOLY cast alloy weakens Widmanstatten structure, refines the grains, reduces the inclusions sizes, changes the inclusions shape from irregular to nearly spherical and makes the inclusions distribution become dispersed. The microstructure of A6MOLY cast alloy adding rare earth is improved. The high-melting-point rare earth inclusions can be generated in A6MOLY cast alloy adding rare earth. The adsorption of rare earth and the heterogeneity crystal nucleus role of the rare earth inclusions inhibit the inclusions growth and make them become round and dispersed.