热处理对γ-TiAl合金中Gd化合物的影响研究

针对含0.15%（原子分数）稀土元素Gd的变形γ-TiAl合金,研究1 300℃/0.5h/空冷热处理前后稀土化合物种类、形态和分布变化。变形γ-TiAl合金中存在两种稀土化合物,分别是富Al元素的Al-Gd化合物和富O元素的O-Gd化合物。在热处理过程中Al元素向Al-Gd化合物边缘扩散,基体的Ti、O元素向Al-Gd化合物扩散,因此部分Al-Gd化合物转变为由Al-Gd包围O-Gd的包裹状化合物。热处理后,Al-Gd化合物球化、尺寸减小、数量减少,体积分数由2.78%减少至1.13%,O-Gd化合物数量增加但形貌基本不变。

Effect of Heat-Treatment on Gd-Compound for TiAl Alloys

The influence from heat-treatment on Gd-compound for TiA1-0.15 %Gd（atomic fraction） alloys was stud- ied. The results showed that there were Gd-compound rich in A1 and O elements both observed in the extruded and heat-treated alloys. Due to the effect of nucleation core by Gd-compound rich in O during solidification, the Gd-compounds rich in A1 and O elements adjacently existed to each other. During the heat-treatment, the Gd-eompound with core that rich in O and few in A1 was formed by the diffusions of Ti and O from matrix to the compound and the diffusion of A1 to the its edge. As a result, the quantity of the Gd-compound was reduced from 2.78% to 1.13 vol. %（volume fractions）. The Gd-compound rich in A1 was globalized, its size and the amount reduced, while the amount of Gd-compounds rich in O was increased with shape unchanged.