TiAl＋Ca合金断裂及变形亚结构研究

FRACTURE AND DEFORMATION SUBSTRUCTURE OF TiAl+Ca ALLOY

运用ＳＥＭ和ＴＥＭ等分析手段研究了ＴｉＡｌ＋Ｃａ三元合金的室温断裂行为和变形亚结构．结果表明，少量Ｃａ的添加可以大幅度提高Ｔｉ－３４％Ａｌ合金的室温力学性能．合金断裂时不再表现为单纯的穿晶解理断裂而在γ单相中出现了河流状的解理纹，断口上还出现较多的撕裂梭；ＴＥＭ分析表明，Ｃａ的添加有助于１／２＜１１０］正常位错的启动；Ｔｉ－３４％Ａｌ－１．０％Ｃａ合金压缩变形时产生大量的位错环，当Ｃａ含量达到２．０％时，在γ相中出现了由于位错分解而产生的层错．

The fracture behaviors and deformation substructures of TiAl+Ca alloy were investigated using SEM and TEM. The results show small Ca additions to Ti-34%Al can improve remarkedly its mechanical properties at ambient temperature. The fracture mode is a mixed mode, including transgranular cleavage and 'river' pattern in gamma single phase. A lot of tear ridges can be found in the fractured surfaces. TEM results indicate Ca additions can enhance the activity of ordinary unit dislocation 1/2 <110]. Dislocation loops in Ti-34%Al-1.0%Ca alloy and stack faults resulting from superdislocation dissociation in Ti-34%Al-2.0%Ca alloy, were observed.