热处理温度对Ti-36Nb-2Ta-3Zr-0.3O合金组织和阻尼性能的影响

Microstructures and Damping Properties of Ti-36Nb-2Ta-3Zr-0.3O Alloy with Different Heat Treatment Temperatures

采用真空自耗熔炼法制备了Ti-36Nb-2Ta-3Zr-0.3O (%,质量分数)合金,通过光学显微镜(OM), X射线衍射仪(XRD)和动态热机械分析仪等测试方法研究了热处理温度对合金的组织和阻尼性能的影响。结果表明:热锻态合金中存在大量的α相,阻尼值较低。在α相转变终了温度以下进行热处理时,合金由β相和α相组成,随着热处理温度升高,α相含量降低,阻尼值升高。在α相转变终了温度以上进行热处理时,α相完全消失,合金仅由β相组成,阻尼值升高。随着热处理温度进一步升高,β晶粒稍有长大,导致合金的阻尼值稍有降低。在不同温度进行热处理的合金均具有较高的阻尼值,其阻尼机制为Snoek型弛豫,与间隙氧原子在体心立方晶格中的基质原子和置换原子附近的重新分布有关。其中,在700℃进行热处理的合金的阻尼值和抗拉强度分别为0.035和670 MPa,是一种具有良好发展前景的高强高阻尼合金。

The Ti-36Nb-2Ta-3Zr-0.3O(%, mass fraction) alloy was fabricated by vacuum consumable arc-melting, and the effect of heat treatment temperature on microstructures and damping properties was investigated by optical microscope(OM), X-ray diffraction(XRD) and dynamic mechanical analyzer. The results showed that the damping capacity of forged alloy was low because of the large number of α phase. When heat treated at temperature lower than the ultimate temperature of α phase, the alloy was composed of β phase and α phase. With the increase of heat treatment temperature, the volume fraction of α phase decreased, leading to the improvement of damping capacity. When heat treated at temperature higher than ultimate temperature of α phase, the α phase disappeared, and the alloy was composed by single β phase and its damping capacity was improved. With the continuous increase of temperature, the grain size increased, and then the damping capacity decreased. The alloy heat treated at different temperatures all had high damping capacity, and the damping mechanism was Snoek-type relaxation, which was related to stress-induced interstitial oxygen atoms reorientation around matrix and substitutional atoms in bcc lattice. The damping capacity and tensile strength of Ti-36Nb-2Ta-3Zr-0.3O alloy heat treated at 700 ℃ were 0.035 and 670 MPa, respectively, indicating that it could be developed as a novel high damping alloy with high strength.