On the high temperature deformation of a directionally solidified γ-TiAl alloy
On the high temperature deformation of a directionally solidified γ-TiAl alloy
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DOI：
10.1016/j.msea.2019.04.072
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发表时间：
2019-06
期刊：
影响因子：
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通讯作者：
Qiang Wang;L. Zeng;H. Ding;Ruirun Chen;Jingjie Guo;H. Fu
中科院分区：
文献类型：
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作者：
Qiang Wang;L. Zeng;H. Ding;Ruirun Chen;Jingjie Guo;H. Fu
采用电磁冷坩埚定向凝固名义成分为Ti-47Al-2Nb-2Cr-0.2C的γ-TiAl合金，在不同温度和应变速率下进行等温压缩。实验结果表明，峰值应力随着变形温度的升高或应变速率的降低而降低。在热压缩过程中，片层内部形成亚晶，位错壁充当亚晶界。动态再结晶晶粒 (DRX) 尺寸较大，并且单个 DRX 晶粒的生长是以许多片晶为代价的。热压缩过程中形成的滑移带在小应变下是单一方向的，而应变的增加导致滑移带在两个方向上相交。当应变达到或超过临界值时，就会形成扭结带，作为再结晶晶粒的首选成核位点。此外，还给出了再结晶晶粒成核的模型。
The γ-TiAl alloy with a nominal composition of Ti-47Al-2Nb-2Cr-0.2C directionally solidified by electromagnetic cold crucible was isothermally compressed at different temperatures and strain rates. Experimental results revealed that the peak stress decreased with the increased deformation temperature or decreased strain rate. Subgrains were formed in the interior of the lamellae during thermo-compression and the dislocation walls served as the subgrain boundaries. The dynamic recrystallization grain (DRX) size was larger and a single DRX grain grew at the expense of many lamellae. Slip bands formed during thermo-compression process were in a single direction at a small strain, while the increase in the strain led to the intersections of slip bands in two directions. Kink bands were developed as the strain reached or exceed a critical value, acting as the preferred nucleation sites for recrystallization grains. Moreover, the model for the nucleation of recrystallization grains was given.