Glassy embrittlement of chromium metal and its improved ductility by alloying elements

铬金属的玻璃脆化及其通过合金元素改善的延展性

基本信息

批准号：
05650671
负责人：
MORINAGA Masahiko
金额：
$ 1.41万
依托单位：
Toyohashi University of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1993
资助国家：
日本
起止时间：
1993 至 1994
项目状态：
已结题

项目摘要

Chromium and its alloys are ones of the promising high temperature materials since they exhibit the excellent combination of low density, high creep strength and good oxidation resistence at high temperatures. However, there is still a large barrier to the practical use because of the poor ductility at room temperature. The purposes of this study are two-fold. One is to elucidate the mechanism for the embrittlement of chromium experimentally using a bend test and a small punch test. The other is to investigate a method for improving the ductility by the addition of alloying elements into chromium.As the result, it was found that plasticity of high-purity polycrystalline chromium was dependent largely on surface imperfections. The existence of small cracks on the surface induced it to be very brittle. Also, large environmental effects were observed on the ductility chromium. For example, the moisture existing in the test environment increased the ductility of pure chromium, which is in contrast to the observations in other metallic materials such as intermetallic compounds (e. g., FeAl TiAl) . In addition, it was shown for the first time that pure chromium exhinbited hydrogen embrittlement. All these phenomena observed in pure chromium were also found in Chromium alloys. Furthermore, the vanadium addition was shown to be most effective in improving the ductility of chromium among a variety of alloying elements including 3d, 4d and 5d transition metals. Thus, the present results provided us important information on the method for improving the ductility of chromium.

铬及其合金是有希望的高温材料之一，因为它们在高温下表现出了低密度，高蠕变强度和良好的氧化抗性的极佳组合。但是，由于室温下的延展性较差，实际使用仍然存在很大的障碍。这项研究的目的是两倍。一种是使用弯曲测试和小型打孔测试来阐明实验中铬含量的机制。另一个是研究一种通过将合金元素添加到铬中来改善延展性的方法。结果发现，高纯度多晶铬的可塑性在很大程度上取决于表面缺陷。表面上的小裂纹的存在导致其非常脆弱。同样，观察到对延性铬的巨大环境影响。例如，在测试环境中存在的水分增加了纯铬的延展性，这与其他金属材料（例如金属间化合物（例如，feal tial））中的观测值形成鲜明对比。此外，首次表明纯铬呼吸氢的含氢。在纯铬中观察到的所有这些现象也在铬合金中发现。此外，氢添加在改善包括3D，4D和5D过渡金属在内的各种合金元素之间最有效。因此，目前的结果为我们提供了有关改善铬延性方法的重要信息。