(哈爾濱工業(yè)大學(xué)材料科學(xué)與工程學(xué)院，哈爾濱150001)
摘 要: 用透射電鏡及備有拉伸裝置的S-570掃描電鏡，研究Ti3Al-Nb(Ti-24Al-14Nb-3V-0.5Mo)(摩爾百分?jǐn)?shù))合金在不同熱處理制度下的組織形貌以及試樣的拉伸斷裂過(guò)程。結(jié)果表明:合金在α2+β兩相區(qū)固溶1h水冷處理，組織由α2相、B2相和o相組成。初生α2相體積分?jǐn)?shù)不同，合金試樣拉伸斷裂機(jī)制不同，初生α2相體積分?jǐn)?shù)低時(shí)，變形主要在B2相，裂紋主要在B2相內(nèi)形核，隨著B(niǎo)2相的減少，合金塑性提高。初生α2相體積分?jǐn)?shù)高時(shí)，變形主要在α2相，裂紋主要萌生于α2相內(nèi)，隨著B(niǎo)2相的增多，合金塑性提高。細(xì)小的隨機(jī)分布的針狀α2相對(duì)合金拉伸斷裂行為有良好作用。隨固溶溫度升高，α2相中位錯(cuò)密度逐漸減少，B2相中位錯(cuò)密度逐漸增多。
關(guān)鍵字: Ti3Al-Nb合金 顯微組織 拉伸斷裂
BEHAVIOR OF Ti3Al-Nb ALLOY WITH
VARIOUS MICROSTRUCTURES
（School of Materials Science and Engineering,
Harbin Institute of Technology, Harbin 150001）
Abstract:The microstructure and the tensile fracture behavior of Ti3Al-Nb (Ti-24Al-14Nb-3V-0.5Mo) (mole percent) alloy under different heat treatment conditions were studied by TEM and by means of S-570 SEM with tensile apparatus. The main results are as follows.The microstructure of the alloy consists ofα2, B2ando-phase when the alloy is solution heated at 940~1100℃for 1h. The tensile fracture mechanisms of Ti3Al-Nb alloy vary with the primaryα2—phase volume fraction. Deformation and microcrack nucleation mainly lie inB2-phase whenα2-phase volume fraction is low and the ductility increases with decreasingB2-phase volume fraction. Deformation and microcrack nucleation mainly happen withinα2-phase whenα2-phase volume fraction is high and the ductility increases with increasingB2-phase volume fraction. Fineα2plates with random orientations tend to improve the ductility of Ti3Al-Nb alloys in tension. As the solution temperature rises, the dislocation density decreases forα2-phase, but increases forB2-phase.
Key words: Ti3Al-Nb alloy microstructure tensile fracture
