冷卻速率對Ti-22Al-24Nb-0.5Mo合金顯微組織和拉伸性能的影響

冷卻速率對Ti-22Al-24Nb-0.5Mo合金顯微組織和拉伸性能的影響Effect of cooling rate on microstructure and tensile properties of Ti-22Al-24Nb-0.5Mo alloy

對Ti-22Al-24Nb-0.5Mo合金(摩爾分數，%)進行固溶后，分別以爐冷、空冷、油淬和水淬4種不同的冷卻速率冷卻到室溫，再進行相同的時效處理，采用掃描電子顯微鏡(SEM)觀察，發現空冷、油冷和水淬得到的顯微組織為在B2/β相基體上析出彌散分布的α2相(等軸的和針狀的)和細小的O相板條構成的雙態組織，且發現隨冷速增快，在冷卻過程中析出的α2相減少，保留BCC相增加；爐冷時得到無序的β相，油冷時得到有序的B2相；4種冷卻速率中，只有爐冷的過程中有O相析出；對不同冷卻速率的試樣進行性能測試，發現隨冷速的增大，650 ℃的抗拉強度逐漸增大，室溫的強度和塑性也有上升的趨勢。

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.

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