锻造TiAl基合金的晶粒长大及其动力学分析  

KINETICS OF GRAIN GROWTH IN A FORGED TiAl-BASED ALLOY

作　　者：唐建成[1] 黄伯云[1] 刘文胜[1] 贺跃辉[1] 

机构地区：[1]中南工业大学粉末冶金国家重点实验室,长沙410083

出　　处：《金属学报》2000年第1期25-29,共5页Acta Metallurgica Sinica

基　　金：国家自然科学基金!59895150;国家863高技术基金!715-005- 0040

摘　　要：研究了锻造ＴｉＡｌ基合金在１１８０到１３２０℃热处理时的晶粒长大过程，并分析了在等温热处理时晶粒长大的动力学．在ａ相转变温度 Ｔａ以上等温热处理时，晶粒迅速长大．晶粒长大因子为 ２．４；在 Ｔａ以下等温热处理时，当热处理时间由 １０ ｍｉｎ延长至４ｈ时，α晶粒不断长大，γ体积分数　γ逐渐变化至平衡值，而γ晶粒尺寸Ｄγ增长较小。继续延长热处理时间。显微组织没有明显的变化，α晶粒尺寸的极限值Ｄα０约为０．６５Ｄｒ／　ｒ提高热处理温度时、ａ晶粒长大速度加快在１１８０，１２２０；１２６０和１３００ ℃热处理时，ａ晶粒长大因子分别为２．９，２．８，２．６５和２．５．Grain growth and its kinetics during heat treatment of a forged TiAl--based alloy in the temperature range from 1180 to 1320 ℃ were investigated. Isothermal heat treatment at temperatures above the alpha transus leads to rapid grain growth, and the grain growth exponent of alpha grains is 2.4. Isothermal heat treatment at subtransus temperatures leads to a little variation of gamma particle size (Dr), a decrease of volume fraction ( r) of gamma particles and a gradual increase of alpha grain size (Da) with increasing holding time from 10 min to 4 h. Elongating holding time continually causes little alternation of the microstructures. The limiting size of alpha grains, D, could be described by 0.65 Dr/ r The growth rate of alpha grains decreases with decreasing heat treating temperature. When the forged TiAl--based alloys are heat treated at 1180, 1220, 1260 and 1300 ℃. the growth exponents of alpha grains are 2.9, 2.8, 2.65 and 2.5 respectively.

关 键 词：TIAL基合金 热处理 晶粒长大 动力学 锻造 

分 类 号：TG146.2[一般工业技术—材料科学与工程] TG132.32[金属学及工艺—金属材料]