铸造镍基高温合金中的初生μ相

PRIMARY μ PHASE IN CAST NICKEL BASE SUPERALLOYS

研究了铸造镍基高温合金中初生μ相的形成条件及μ相的特征，结果表明在碳量低于０．０７％（质量分数）的铸造镍基高温合金中，当难熔元素Ｃｒ，Ｍｏ，Ｗ，Ｎｂ，Ｈｆ总量超过１１％（原子分数），（Ｗ＋Ｍｏ）超过８％（原子分数），Ｍｏ（原子分数）／（Ｗ＋Ｍｏ）（原子分数）超过０．１７时会形成初生μ相，该相在高温下是不稳定的，它会转变成Ｍ６Ｃ碳化物Ｍｏ，Ｗ，Ｃｒ，Ｈｆ，Ｎｂ，Ｃｏ是μ相形成元素，Ｍｏ在形成μ相方面作用更强Ｗ，Ｃｒ，Ｈｆ，Ｎｂ的作用差别不明显，Ｃｏ的作用最小。

The u phase can be formed in cast nickel base superalloys containing lower contentof carbon than 0.07%, when the total amount of refractory elements Cr, Mo, W, Nb, and Hf (atomicfraction,%), the content of (Mo+W) and the ratio of Mo/(Mo+W) exceed 11%, 8% and 0.17 respectively.This phase is unstable at high temperature and it can transform into M_6C carbide. The elements of Mo,W, Cr, Hf, Nb and Co are u-former. The effect of Mo on formation of u phase is stronger than W, theu-formation tendency of W, Cr, Hf, and Nb has no obvious difference, and the effect of Co is the thesmallest in p-former.Therefore it is impossible to replace W by equal atomic percent Mo in cast nickel basesuperalloys.