(中國科學院 金屬研究所鈦合金研究部， 沈陽 110016)
摘 要: 測試了兩種溫度固溶后鍛態(tài)Ti-6.9Al-3.6Zr-2.7Sn-0.7Mo-0.6Nb-0.21Si(BT18y)鈦合金棒的室溫拉伸性能。 利用金相顯微鏡、 透射電鏡和掃描電鏡研究了該合金的室溫拉伸塑性與顯微組織的關系。 結果表明： 經920 ℃、 2 h空冷處理的材料為細晶等軸組織， 變形時晶粒間的協(xié)調性好， 具有優(yōu)良的室溫拉伸性能， 塑性尤其突出； 經1 020 ℃、 2 h空冷處理的材料為具有晶界α相的粗晶片層組織， 在拉伸變形時， 同時要求相鄰晶粒之間、 晶粒內部的相鄰α片束團之間相互協(xié)調， 增加了塑性變形的阻力， 但殘余β相使得材料保持了一定的塑性。 多個視角觀察表明： α片束團表現(xiàn)出了方向性， 與拉伸軸夾角較小的片束具有良好的拉伸性能， 與拉伸軸夾角較大的片束內的β相中間層是拉伸時裂紋的優(yōu)先形成區(qū)。
關鍵字: Ti-6.9Al-3.6Zr-2.7Sn-0.7Mo-0.6Nb-0.21Si鈦合金； 熱處理； 顯微組織； 室溫拉伸塑性
（ Titanium Alloy Laboratory, Institute of Metal Research, Chinese Academy of Science, Shenyang 110016, China）
Abstract: Tensile properties of forging Ti-6.9Al-3.6Zr-2.7Sn-0.7Mo-0.6Nb-0.21Si titanium alloy after two types of heat treatments were tested at room temperature. Optical microscope, transmission electron microscope (TEM) and scanning electron microscope (SEM) were used to investigate the relationship between microstructures and room-temperature tensile plasticity. The microstructure of the sample solutionized at 920 ℃ for 2 h followed by cooling in air is fine equiaxed structure. Compatibility among grains is easy during deformation, so it has good tensile properties at room temperature, especially better tensile plasticity. The sample solutionized at 1 020 ℃ for 2 h followed by cooling in air possesses a coarse and lamellar structure with continuous grain boundary α phase. In the tensing process, coordinations among adjacent grains and among α colonies in grains are needed at the same time, so the plastic deformation becomes difficult. But β phase interlayer makes the material maintain some plasticity. α colony has anisotropy. The one that has small included angle to the tensile direction possesses better tensile properties. β phase interlayer in the one that has big included angle to the tensile direction is vulnerable area in the material, and cracks arise in this place firstly while tensing.
Key words: Ti-6.9Al-3.6Zr-2.7Sn-0.7Mo-0.6Nb-0.21Si titanium alloy; heat treatment; microstructure; room-temperature tensile plasticity
