冷却速率对Ti-22Al-24Nb-0.5Mo合金显微组织和拉伸性能的影响

摘要

The effect of cooling rate on the microstructure and tensile properties of Ti-22Al-24Nb-0.5Mo (mole fraction,％) alloy was studied.Cooling from 980 ℃ to room temperature was arranged by four kinds of rate,including furnace cooling,air cooling,oil quenched and water quenched,and then followed by the same aging treatment.The results show that the multiphase structure consists of dispersively distributed α2 (equiaxed and acicular) phase,fine O phase and B2/β phase matrix by air cooling,oil quenching and water quenching.The volume fraction of α2 phase reduces and the volume fraction of BCC phase increases with increasing the cooling rate.The disorder β phase is formed at furnace cooling,the order B2 phase is obtained at oil quenched.The strength at 650 ℃ increases with the cooling rate increasing,which is similar to that at room temperature.%对Ti-22Al-24Nb-0.5Mo合金(摩尔分数,％)进行固溶后,分别以炉冷、空冷、油淬和水淬4种不同的冷却速率冷却到室温,再进行相同的时效处理,采用扫描电子显微镜(SEM)观察,发现空冷、油冷和水淬得到的显微组织为在B2/β相基体上析出弥散分布的α2相(等轴的和针状的)和细小的O相板条构成的双态组织,且发现随冷速增快,在冷却过程中析出的α2相减少,保留BCC相增加;炉冷时得到无序的β相,油冷时得到有序的B2相;4种冷却速率中,只有炉冷的过程中有O相析出;对不同冷却速率的试样进行性能测试,发现随冷速的增大,650℃的抗拉强度逐渐增大,室温的强度和塑性也有上升的趋势.