包套锻造粉末冶金TiAl基合金的高温力学性能

摘要

TiAl pre-alloyed powder with nominal composition of Ti-47Al-2Cr-2Nb-0.2W (atom fraction, %) was prepared by plasma rotating electrode atomizing process, and then hot isostatic pressed to obtain high quality ingot. The high temperature mechanical properties of TiAl based alloys were studied after the ingot had been canned-forged with temperature in the range of 1 150~1 200℃and strain rate in the range of 0.1~0.01 s-1. The results show that the high temperature mechanical properties of such alloy increase due to the refining and homogenization of the microstructure after canned-forging, while the elongation is still not high enough due to the existence of micro-cracks. When high temperature tensile tests are conducted, the micro-cracks or micro-pores occurred in the test samples will expand and connect during tensile process which results in the rupture of the samples.%采用等离子旋转电极雾化工艺制备名义成分为Ti-47Al-2Cr-2Nb-0.2W (原子分数，%)的预合金粉末，并经热等静压致密化得到TiAl基合金坯料。对热等静压坯体进行包套锻造，始锻温度为1150~1200℃，并控制应变速率为0.1~0.01 s-1，研究包套锻造后TiAl基合金的高温力学性能。结果表明，包套锻造后组织得到了一定程度的细化和均匀化，从而使合金的高温力学性能得到提高，但由于显微组织中有少量微裂纹存在，导致包套锻造TiAl基合金仍呈现较低的伸长率。TiAl基合金在进行高温拉伸时，首先在试样内部形成微裂纹或微孔，随拉伸过程的进行微裂纹或微孔扩展、连通，最终使试样断裂。