Effects of short time heat treatment on superelastic properties of a Ti-Nb-Al biomedical shape memory alloy
Effects of short time heat treatment on superelastic properties of a Ti-Nb-Al biomedical shape memory alloy
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DOI：
10.1016/j.msea.2006.02.151
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发表时间：
2006-12-25
期刊：
影响因子：
6.4
通讯作者：
Miyazaki, S.
中科院分区：
文献类型：
--
作者：
Hosoda, H.;Kinoshita, Y.;Miyazaki, S.
研究了短时热处理对Ti-24 Nb-3Al（at.%）合金的显微组织、织构形成以及各向异性对超弹性性能的影响。合金，其是基于Ni-Ti和β-钛的生物医学形状记忆合金。通过Ar-电弧熔炼制造锭，在1273 K下均匀化7.2ks，然后冷轧，厚度减少99%。然后，该合金在973，1123和1273 K分别热处理60，120，180和300 s等。X射线衍射分析，X射线极图测量和扫描电子显微镜（SEM）结合电子背散射谱（EBSP）的记录，对合金进行表征。采用循环加载-卸载拉伸试验研究了1123 K × 120 s热处理后合金的超弹性。结果发现，< 110 >在973 K、300 s热处理后，仍出现冷轧形成的（β）{001}（β）型变形织构。另一方面，还发现在< 110 >1123 K热处理180 s和1273 K热处理60 s时出现{112}（β）（β）型再结晶织构。只有在1123 K × 120 s热处理时，才发现合金中既有晶粒尺寸为0.5 μ m的形变织构，又有晶粒尺寸为20 μ m的再结晶织构。通过拉伸试验，具有这种双峰织构的合金比完全再结晶和冷轧的合金在所有拉伸方向上都表现出4%的各向同性超弹性。(c)2006 Elsevier B. V.保留所有权利。
The effect of short time heat treatment on microstructure, texture formation and anisotropy on superelastic properties was investigated for a Ti-24Nb-3Al (at.%) alloy, which is a Ni-ftee and beta-titanium based biomedical shape memory alloy. An ingot was made by Ar-arc melting, homogenized at 1273 K for 7.2 ks, and then cold rolled with 99% reduction in thickness. Then, the alloy was heat-treated at 973, 1123 and 1273 K for 60, 120, 180 and 300 s, etc. X-ray diffraction analysis, X-ray pole figure measurement and scanning electron microscopy (SEM) combined with the recording of electron backscattering patterns (EBSP), were made for alloy characterization. Cyclic loading-unloading tensile test was performed to evaluate superelasticity for the alloy heat-treated at 1123 K for 120 s. It was found that < 110 >(beta){001}(beta)-type deformation texture, which is developed by cold rolling, still appears after the heat treatment at 973 K for 300 s. On the other hand, it was also found that {112}(beta)< 110 >(beta)-type recrystallization texture appears when heat-treated at 1123 K for 180 s and 1273 K at 60 s. Only when heat-treated at 1123 K for 120 s, SEM-EBSP revealed that the alloy contains both deformation texture with a grain size of 0.5 mu m in diameter and recrystallization texture with a grain size of 20 mu m. By tensile tests, the alloy with such bimodal texture exhibits more isotropic superelastic property of a 4% in all tensile directions than fully recrystallized and cold rolled alloys. (c) 2006 Elsevier B.V. All rights reserved.