长期时效对一种GH4169合金蠕变行为的影响

Influence of long-term aging on creep behavior of a GH4169 alloy

通过对改进GH4169合金进行不同制度热处理、蠕变性能测试和组织观察,研究了长期时效处理对合金蠕变行为的影响。结果表明:合金经常规热处理的组织由γ、γ′、γ″相、粒状碳化物和δ相组成,其中,弥散分布的粒状γ′和椭圆状γ″相以相干方式分布在合金基体中,粒状碳化物在晶界和晶内析出,而δ相分布于晶界。蠕变期间,粒状碳化物可抑制晶界滑移,阻碍位错运动,使得合金具有良好的服役性能。由于长期时效处理增加了针状δ相的数量和尺寸,割裂了基体的连续性,蠕变期间激活的位错滑移至晶界受阻,可促使裂纹沿晶界的萌生与扩展,使长期时效后合金的蠕变寿命较低。

The modified GH4169 alloy was subjected to different heat treatments, creep tests and microstructure observation, and the effect of long-term aging on creep behavior of the alloy was investigated. The results show that the microstructure of the alloy after standard heat treatment is composed of γ, γ′, γ″ phases, granular carbides and δ phases, in which the dispersed granular γ′ phase and elliptical γ″ phase are distributed in the alloy matrix in a coherent manner, the granular carbides precipitate at the grain boundary and in the grains, and the δ phases are distributed at the grain boundary. During creep, the granular carbides can inhibit grain boundary sliding and hinder dislocation movement, which makes the alloy have good service performance. Because the long-term aging treatment increases the number and size of acicular δ phases and destroys the continuity of the matrix, the dislocations activated during creep are prevented from sliding to the grain boundary, which can promote the initiation and propagation of cracks along the grain boundary, so the creep life of the alloy after long-term aging is low.