Basic Research for Development of New TiAl Base Alloys

在室温下研究了钛铝比、添加第三元素(Cr、Hf、Nb)和使用高纯母材对TiAl力学性能的影响。钛铝比的影响：富钛合金的强度高于富铝合金。富钛合金的断裂应变(延性)约为1.8%，大于富铝合金的0.6%。第三元素的作用：(1)铬；强度随铬含量的增加而线性增加。铬含量为3at.%的合金是二元合金的两倍。在富钛合金中添加3at.%的铬可使塑性提高到2.7%。富铝合金中添加铬降低了塑性。(2)汞；添加Hf对强度的影响与添加铬的合金相似。在富钛合金中添加高达4at.%的Hf后，塑性略有下降。富铝合金经Hf处理后，塑性降低到0.8%。(3)Nb含量为3at.%时，合金的强度提高到二元合金的2.5倍。相反地。富铝合金中未观察到强化效应。由于Nb的加入，富钛和富铝合金的塑性降低到1/2。纯度的影响：使用99.91%纯度的钛使延伸率提高到2.7%，这是二元合金中的最高值。

The effect of the Ti/Al retio, the addition of third elements (Cr, Hf and Nb) and the use of high purity base metals on mechanical properties of TiAl was studied at room teperature.1. Effect of the Ti/Al ratio : Strength of Ti-rich alloys was higher than than of Al-rich alloys. Fracture strain (ductility) in Ti-rich alloys was about 1.8 % which was larger than that in Al-rich a alloys being 0.6 % .2. Effect of third elements : (1) Cr ; Strength increased linearly with increasing Cr content. The alloy with 3 at.% Cr reached two times of that in a binary alloy. The Cr addition of 3 at.% to Ti-rich alloys improved ductility to 2.7 %. The Cr addition to Al-rich alloys lowered ductility.(2) Hg ; The effect of Hf addition on strength was similar to that in the Cr added alloys. The Hf addition up to 4 at.% to the Ti-rich alloys lowered ductility a little. The Hf eddition to Al-rich alloys decreased ductility to 0.8 %.(3) Nb ; Strength of the alloy with 3 at.% Nb increased to 2.5 times of that in a binary alloy. On the contrary. No strengthening effect was observed in Al-rich alloys. Ductility in Ti- and Al-rich alloys was decreased to 1/2 due to the Nb addition of 3 at.%.3. Effect of purity : The use of Ti with 99.91 % purity increased ductility to 2.7 % which has been the highest value in the binary alloys.