采用非自耗真空电弧熔炼Ti-45Al?5Nb?xMo?0.3Y(x=0.6,0.8,1.0,1.2)合金试样,研究Mo含量变化对含β 相TiAl合金显微组织和力学性能的影响规律.研究表明,Mo元素的偏聚使 β 相呈不连续网状分布于 γ/α2片层团边界.当Mo含量超过0.8%时,β 相在枝晶间微偏析区易形成 γ 相.在Tα 转变温度以上进行均匀化热处理可使β 和 γ 相得到有效消除.对初始铸态和均匀化热处理态TiAl合金的组织性能进行对比分析发现,添加过量的Mo元素容易引起微偏聚,从而降低材料的强度和显微硬度,而均匀化热处理可使得其力学性能得到明显改善.
The influence of Mo content on the microstructure and mechanical properties of the Ti-45Al-5Nb-xMo-0.3Y (x=0.6, 0.8, 1.0, 1.2) alloys was studied using small ingots produced by non-consumable electrode argon arc melting. The results show that small quantities of β phase are distributed along γ/α2 lamellar colony boundaries as discontinuous network in the TiAl alloys owing to the segregation of Mo element. The γ phase forms in the interdentritic microsegregation area when the Mo addition exceeds 0.8%. The βand γ phases can be eliminated effectively by subsequent homogenization heat treatment at the temperature above Tα. The evolution of the strength, microhardness and ductility at different Mo contents under as-cast and as-homogenization treated conditions was analyzed, indicating that excessive Mo addition is prone to cause the microsegregation, thus decreasing the strength and microhardness obviously, which can be improved effectively by subsequent homogenization heat treatment.
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