保温时间对TiAl基合金组织与力学性能的影响

Effect of Holding Time on Microstructure and Mechanical Properties of TiAl Based Alloy

以铸造TiAl合金为研究对象,系统研究了在1523 K下不同保温时间内的合金中β2相的相变规律和其对室温力学性能的影响,结果表明:在1523 K分别保温5 min^4 h,然后对铸造态Ti-Al-Nb-Cr-Mo-B合金进行水冷淬火,当保温时间为2 h时,韧性没有降低,强度却从1200 MPa提升到了1500 MPa。在保温过程中α分解为γ+β相,随后冷却过程中,无序的β相会转变为有序的β2相。实验结果表明β2相是一种硬脆相,少量的β2相能促进合金强度的提升。

The transformation rule ofβ2-phase and its effect on the mechanical properties at room temperature in the cast TiAl alloy were studied.The results show that the toughness of the cast Ti-Al-Nb-Cr-Mo-B alloy is not decreased when the holding time is 2 h,but the strength is increased from 1200 MPa to 1500 MPa.In the process of heat preservation,a decomposes intoγ+βphase,and then in the process of cooling,the disorderedβphase transforms into orderedβ2 phase.It is demonstrated thatβ2 phase is a hard brittle phase,and a small amount ofβ2 phase can promote the strength of the alloy.