新型β钛合金Ti-25Nb-10Ta-1Zr-0.2Fe的固溶时效行为

Aging Response of Ti-25Nb-10Ta-1Zr-0.2Fe Alloys for Biomedical Application

摘要:

设计一种新型生物医用亚稳定β钛合金，合金成分为Ti-25Nb-10Ta-1Zr-0.2Fe (质量分数)，采用真空自耗电弧熔炼制备合金锭坯，研究合金的固溶时效行为。通过X射线衍射 (XRD)仪，透射电子显微镜 (TEM)，扫描电子显微镜(SEM)研究合金的相组成及微观组织。测量合金时效后的抗拉强度和不同时效时间的硬度。结果表明：800 ℃，1 h固溶后合金得到马氏体α″相，400 ℃下时效，短时间即得到ω相和β相。ω相为脆性相，大量ω相的产生使合金的硬度值提高很多，但是强度值相比较冷轧态下降明显，使得材料断裂方式变为脆性断裂。合金在72 h时效后ω相仍然保持较多量

Abstract:

A new metastable β titanium alloy, Ti-25Nb-10Ta-1Zr-0.2Fe, was designed for biomedical applications. The alloy ingot was prepared by vacuum consumable electrode arc melting. The solid-solution aging behavior of the alloy was investigated. The phase composition and the microstructure were studied by XRD, TEM and SEM. The tensile strength after aging and the hardness for different aging time were tested. Results show that only the α″ phase is found after solid solution treatment at 800 oC for 1 h. The ω phase and β phase are observed when the alloy is subjected to aging treatment at 400 oC for 0.5 h. The ω phase, as a brittle phase, keeps a high volume fraction during the aging treatment, which leads to a sharp increase of the Vicker hardness. In this case, the tensile strength of the alloy decreases dramatically to only about 400 MPa, which is much smaller than that of the specimen in the cold-rolled condition (about 750 MPa). Hence, a large mount of ω phase decreases the tensile property of the newly designed alloy Ti-25Nb-10Ta-1Zr-0.2Fe