铸造Ti-47Al-2Cr-2Nb合金中2β相的特征及对组织热稳定性的影响

Characteristics of β_2 Phase in the Casting Alloy Ti-47Al-2Cr-2Nb and its Effect on the Alloy Thermal Stability

研究了具有工业应用背景的铸造Ti-47Al-2Cr-2Nb合金中β2相的特征及其对组织热稳定性的影响。结果表明,该2β相为富Cr相,呈连续线状弥散分布于TiAl合金片层结构中,2β相与2α、γ相不存在严格的共格位向关系;经1 150℃/48 h时效处理后,片层组织首先在β2/(2α+γ)界面发生粗化分解,而在(α+γ)两相区加热处理中,α颗粒亦会在该界面位置优先析出长大,该2β相的引入不利于组织热稳定性。

The characteristics of β2phase and its effects on the alloy thermal stability were investigated in the casting alloy Ti-47Al-2Cr-2Nb with industrial application value. The results show that β2 phase is with high Cr content and of dispersive distribution and continuous linear morphology in the TiAl alloy lamellar microstrueture. No strict coherent orientation of a2 and 7 phase is kept in β2 phase. By aging treatment （1 150℃ and 48 h）,the lamellar structure is dissolved and coarsened preferentially at the phase interface between β2 and （a2＋γ）. During the heating process of （a2＋γ） phase region,a2 particles are also precipitated and grown preferentially at the boundary. Accordingly,the addition of β2 phase is harmful for the thermal stability of TiAl alloy.