【摘要】 本文利用分析电子显微术及化学分析方法研究了GH220合金中镁的分布及存在方式,应用蠕变过程的动态观察,研究了含镁及无镁合金的蠕变变形特征。实验分析表明:在最佳镁含量合金中,一部分镁不均匀地填隙于晶界上碳化物与基体（或γ′）的非共格的界面上,形成100 A左右尺寸的Ni₂Mg相;在碳化物颗粒之间有点阵常数为12～14 A的面心立方点阵的含镁相析出。从而降低了晶界空位浓度,减缓了空位扩散型攀移造成的晶界滑动,使得晶内γ′和基体及晶界上的碳化物有时间得以充分变形以与晶界被减缓的滑动协调,降低了稳态蠕变速率。更多还原

【Abstract】 In this work distribution and existance morphology of Mg in a superalloy have been investi-gated by analytical elcctrc.,~ microscopy and chemical analysis. Creep behaviour in the superalloywith and without Mg has been studied by means of dynamic observation on the crecp procedure.It is indicated that in an alley with optimum Mg percentage, a past of Mg inhomongeneouslyfills up the incoherent interface between a carbide at a grain boundary and matrix (or 7’phase) to form a Laves phase Ni2Mg wlth about 10nm size and the vacancy between the carbidesat a grain boundary to form a Mg phase with F. C. C. lattice (a.=l.2--1.4nm). Then number ofthe vacancy is decreased and the grain boundary gliding, resulted from vacancy diffusion climb-ing, is slowed down It is Vossible to get enough time for harmonization of a deformation of theY’ vhase, the matrix and the carbide at the grain boundaries It dcc~eascs steady state creeprate and improves creep toughness.更多还原