TiAl基合金/金属型界面反应规律研究

Study of the Reaction at TiAl Based Alloy/Permanent Mold Interface

利用感应凝壳熔炼 (ISM)法 ,在金属型中离心浇铸了 Ti- 48Al- 2 Cr- 2 Nb (at% )合金汽车排气阀 ,并利用 SEM,XRD和 EMPA等检测方法对排气阀的表面层结构进行了分析。结果表明 ,排气阀表面上的铁含量约为 0 .3wt% ,渗铁层厚度为 3μm左右。由于金属型与合金熔体之间的反应 ,以及铸型的强冷却作用 ,使得排气阀表面上出现了一定厚度的硬化层 ,其厚度要远大于渗铁层 。

Ti 48Al 2Cr 2Nb(at%) alloy exhaust valves were formed in permanent mold during centrifugal casting process with Induction Skull Melting (ISM) method, and the reaction at TiAl alloy/permanent mold interface were analyzed by SEM, XRD and EMPA The results show that the content of Fe on valve surface is about 0 3wt%, which thickness is about 3μm Certain thick hardness layer exists on the cast valve surface because of the reaction at alloy/mold interface and the powerful heat conduction of the mold, which thickness is more larger than that of Fe diffusion layer It is very important to improve the resistance and intensity of the cast surface