时效期间含Re镍基单晶合金中TCP相的演化

Evolution of TCP phase in a single crystal nickel-based superalloy containing Re during aging

为了研究单晶合金中TCP相的演化过程,采用对含Re镍基单晶合金进行1100℃长期时效处理及组织形貌观察等方法,研究了时效期间合金中析出TCP相的演化特征.结果表明:元素W、Re可促进TCP相的析出,合金在1100℃长期时效期间,TCP相沿{111}晶面<110>取向呈片状析出,并确定出析出的TCP相为μ相,其中在不同晶面观察多组针状μ相可相互垂直或互成60°排列.在长期时效期间,片状μ相逐渐粗化、出现沟槽直至发生溶断,并逐渐转变成球状形貌.随w(Re)增加,合金的偏聚自由能降低,可使片状μ相粗化及形成γ′/μ两相凹凸界面;而在曲率半径较小处产生附加压力,引起溶质元素在μ相中化学位提高,是致使片状μ相发生分解及逐渐球化的主要原因.

In order to identify the evolution process of TCP phase in single crystal superalloy,the evolution characteristic of TCP phase in a nickel-based superalloy containing Re was investigated through performing long-term aging treatment at 1 100℃and microstructural observation.The results show that the elements W and Re may promote the precipitation of TCP phase in the superalloy.During long-term aging at 1 100℃,the TCP phase precipitates in slice-like form along{111}plane and〈110〉orientation,and the TCP phase is determined asμphase.The observed strip-likeμphase may be at the angle of 60°or vertical to each other on the different crystal planes.During long-term aging,the slice-likeμphase coarsens gradually,and the groove appears on the strip-likeμphase until the dissolving abruption ofμphase occurs and furthermore theμphase transforms into the spheroidized morphology.With increasing the Re content,the additive prossure is generated in the regions with smaller curvature radius,which leads to the enhancement in chemical potential of the solute elements in theμphase and promotes the their diffusion.This is thought to be the main reason for the decomposition and gradual spheroidizing ofμphase.