用循环热处理细化铸造TiAl基合金的显微组织

设计了一种新的循环热处理工艺，并用正交设计试验（Ｌ１６（４５））研究了各热处理工艺参数，即加热速度、保温温度、保温时间、冷却速度和循环次数对铸造ＴｉＡｌ基合金显微组织和显微硬度（ＨＶ５）的影响．结果表明：循环热处理工艺均能不同程度地提高显微硬度，提高的最大幅度达４０％；各因素的影响按大小排列依次为加热速度，保温时间、保温温度、冷却速度、循环次数．利用循环热处理可获得不同类型的显微组织．在正交试验的基础上确定了优化的热处理工艺，并用它获得了细小的显微组织．

MICROSTRUCTURAL REFINEMENT OF AS CAST TiAl BASED ALLOY BY CYCLIC HEAT TREATMENTS

A novel cyclic heat treatment technology was designed, and the effects of the various technological parameters, i. e. heating rate, holding temperature, holding time, cooling rate and cycle number, on the microhardness and the microstructures of a Ti 33Al 3Cr cast alloy were studied using the orthogonal design method (L 16 (4 5)). The results show that the cyclic heat treatments can increase the microhardness in varying degrees and the largest increasing amplitude is up to 40%. The effects of the various technological parameters from large to small are in the following order: heating velocity, holding time, holding temperature, cooling velocity and cycle number. Several typical microstructures were obtained by the cyclic heat treatments. Based on the orthogonal test, the optimized technologies were determined and fine lamellar microstructures were produced.