Microstructure and tensile properties of Ti-44Al-5V-1Cr-0.3Ni-0.1Hf-0.15Gd alloy
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摘要: 針對變形量達86%的鍛造Ti-44Al-5V-1Cr-0.3Ni-0.1Hf-0.15Gd(原子分數,%)合金,對其進行熱處理獲得近層片組織,研究變形合金及其近層片組織的微觀組織特征,并進行了室溫、700℃和800℃拉伸實驗.組織觀察發現,近層片組織由層片團、分布于層片團界的β相以及彌散分布于基體的橢圓狀Gd析出物組成.層片團的平均尺寸為40μm,層片組織、β相和Gd析出物的體積分數分別為93.73%、5.25%和1.02%.拉伸結果顯示,室溫下合金試樣的平均抗拉強度為865MPa,平均延伸率可達4.17%,700℃時其平均抗拉強度和延伸率分別為643MPa和22%.Ti-44Al-5V-1Cr-0.3Ni-0.1Hf-0.15Gd合金不僅具有與高β相TiAl合金相當的塑性變形能力,且室溫塑性也得到顯著提高,這主要歸因于β相體積分數的下降和Gd化合物對微觀組織室溫塑性的貢獻.Abstract: Ti-44Al-5V-1Cr-0.3Ni-0.1Hf-0.15Gd(atom fraction,%) alloy that forged by 86% was heat treated to be near fully lamellar microstructure(NFL).The microstructures of the deformed alloy and NFL were investigated.Tensile tests at room temperature,700 ℃ and 800 ℃ were carried out.The results show that NFL consists of lamellar microstructure,β phase that locates at lamellar boundaries,and elliptical Gd-compound that disperses in the matrix.The average grain size of the lamellar is 40 μm.The volume fraction of the lamellar,β phase and Gd compound is 93.73%,5.25% and 1.02%,respectively.The tensile tests indicate that the average tensile elongation at room temperature is up to 4.17% and the tensile strength is 865 MPa.At 700 ℃,the average tensile elongation is 22% and the tensile strength is 643 MPa.Compared Ti-44Al-5V-1Cr-0.3Ni-0.1Hf-0.15Gd alloy with TiAl alloys that contain more β phase,the hot deformability is maintained and the room tensile ductility of the studied alloy is much more elevated.It is due to the lower β phase and Gd-compound of the microstructure.
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Key words:
- TiAl alloys /
- microstructure /
- tensile properties /
- temperature
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