摘要
研究了二次加热工艺参数对SIMA法制备7A04合金半固态触变组织的演化规律。结果表明:随着加热温度的升高和保温时间的延长,晶粒的形状逐渐趋于球形。当加热温度低于610℃时,晶粒尺寸不断长大,而后逐渐减小。在保温的初始阶段,共晶液相没有完全浸润晶粒边界,晶粒的聚结长大处于主导地位。当保温时间达到4 min左右时,共晶液相几乎充满了所有的晶界,Ostwald长大扩散机理处于主导地位。晶粒长大规律符合动力学方程。
The thixotropic microstructural evolution＇s law of reheating parameters on 7A04 alloy by SIMA method was studied. The results show that the grain shape approaches to sphericity slowly with the increasing of heating temperature and soaking time. The grain sizes grow up when the heating temperature is lower than 610 ℃, and then decrease slowly. At the initial stage of soaking, eutectic liquid is not distributed between the whole primary grains, so the main mechanism of grain coarsening is coalescence. When the soaking time reaches up to 4 min, eutectic liquid nearly fills out all grain boundaries and the main mechanism of grain coarsening is Ostwald ripening instead of coalescence. Moreover, the mechanism of grain coarsening belongs to volume diffusion during isothermal process and is satisfied with dynamic equation.
出处
《锻压技术》
CAS
CSCD
北大核心
2008年第3期72-74,共3页
Forging & Stamping Technology
基金
江苏省高校自然科学基础研究项目资助(07KJD460007)
常州工学院自然科学研究项目资助(YN06043)
关键词
SIMA法
触变组织
加热温度
保温时间
SIMA method
thixotropic microstructure
heating temperature
soaking time
