间隙元素O对β型Ti-15Mo合金超低温力学性能的影响  

Effect of Interstitial Element O on Cryogenic Mechanical Properties inβ-Type Ti-15Mo Alloy

作　　者：戴进财 闵小华[1] 辛社伟[2] 刘凤金 DAI Jincai;MIN Xiaohua;XIN Shewei;LIU Fengjin(School of Materials Science and Engineering,Dalian University of Technology,Dalian 116024,China;Northwest Institute for Non-Ferrous Metal Research,Xi'an 710016,China)

机构地区：[1]大连理工大学材料科学与工程学院,大连116024 [2]西北有色金属研究院,西安710016

出　　处：《金属学报》2025年第2期243-252,共10页Acta Metallurgica Sinica

基　　金：国家自然科学基金项目,No.52071051;西安市高性能钛合金材料重点实验室(重点)基金项目,No.NIN-HTL-2022-ZD01。

摘　　要：O元素会影响亚稳β型钛合金的塑性变形方式,从而影响合金的低温力学性能。利用HRTEM、FIB、EBSD、SEM、OM和配备了低温系统的电子万能试验机等研究了2种不同O含量(0.2%和0.4%,质量分数)的β型Ti-15Mo合金(分别命名为0.2O和0.4O合金)在20 K下的拉伸力学性能。结果表明,20 K下,0.2O合金具有较好的抗拉强度(1825 MPa)和延伸率(7.5%)匹配,呈现典型的微孔聚集型断裂特征;而0.4O合金具有高的抗拉强度(1973 MPa),但延伸率较低(1.5%),呈现典型的解理断裂特征。2者超低温力学性能的差异主要取决于O含量对{332}<113>孪晶形成的影响,前者中形成了大量孪晶,而后者仅在断口附近产生了少量孪晶。0.2O合金高的强度归因于{332}<113>孪生的临界分切应力大幅提高,而较高的延伸率则是因为大量孪晶的产生阻碍了局部塑性变形。此外,该合金的拉伸曲线呈现典型的锯齿状特征,并且拉伸试样出现了多处缩颈。缩颈区域产生的孪晶阻碍了局部塑性变形的进行,进一步提高了强塑性匹配。因此,有效利用间隙元素O能够调控亚稳β型钛合金的超低温力学性能。Ti and titanium alloys are preferred for cryogenic applications,particularly at a liquid hydrogen temperature of 20 K,in aerospace due to their high specific strength,good corrosion resistance,low magnetic permeability,and low thermal expansion coefficient.Currently,the most common cryogenic titanium alloys are extra-low interstitialα-type and nearα-type alloys.However,they exhibit inadequate age hardening and low cold-forming ability.Furthermore,they do not meet the enhanced strength-ductility requirements for cryogenic structural components.Metastableβ-type titanium alloys with a{332}<113>twinning-induced plasticity(TWIP)effect have shown enhanced mechanical properties,such as a favorable balance of strength-ductility at ambient and cryogenic temperatures.Therefore,they are considered promising titanium alloy candidates for cryogenic applications.The content of interstitial elements,particularly the O content,has a substantial impact on the cryogenic ductility of titanium alloys.Therefore,all cryogenic titanium alloys have extremely rigorous requirements regarding the O content.However,the effect of O content on the cryogenic tensile behavior of{332}<113>TWIP alloys remains unclear.This study investigated the cryogenic tensile behavior of Ti-15Mo alloy with O contents of 0.2%and 0.4%(mass fraction,the same below)at 20 K.The tests were conducted using HRTEM,FIB,EBSD,SEM,OM,and a tensile testing machine fitted with a cryogenic system.Results show that the alloy comprising 0.2%O content(0.2O alloy)exhibits a good combination of tensile strength(1825 MPa)and elongation(7.5%).This alloy displays typical microvoid coalescence fracture characteristics.Alternatively,the alloy with 0.4%O content(0.4O alloy)presents a high tensile strength of 1973 MPa,a relatively low elongation of 1.5%,and typical cleavage fracture characteristics.The discrepancy in cryogenic tensile properties between the two alloys can be attributed to the effect of O content on the formation of{332}<113>twins.Several{332}<113>twins appear in the 0

关 键 词：Β型钛合金 超低温 {332}<113>孪生 O含量 微观组织 断口形貌 力学性能 

分 类 号：TG146.2[一般工业技术—材料科学与工程]