Powdering limit of hydrogen absorbing intermetallic compounds

吸氢金属间化合物粉化极限

基本信息

批准号：
12305046
负责人：
YAMAGUCHI Masaharu
金额：
$ 26.14万
依托单位：
Kyoto University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2002
项目状态：
已结题

项目摘要

Mechanisms of the reversible hydrogen absorption and desorption in Ti_3Al-base alloys was studied by means of pressure-composition isotherm measurements and microscopy observations before and after hydrogen absorption on specimens subject to heat treatment and cold rolling. The alpha-hydride to beta-hydride phase transformation in the Ti_3Al-base alloys occurs at a very low pressure and is reversible under normal conditions. However, the transformation between beta and gamma hydrides can be made reversible if the specimen is heat treated so that it contains O-phase in its microstructure or is appropriately deformed by cold rolling. The beneficial effects of O-phase on hydrogen absorption/desorption were demonstrated in three Ti-AT-Nb alloys with compositions in the vicinity of Ti_2NbAl. The beneficial effects are found to be related to the structure and strain field of O-phase rather than the interface between the O-phase and matrix. Their hydrogen absorption and desorption properties are improved when they are mildly deformed. Microstructure observations show that the beta and gamma hydride transformation occurs in a way very similar to the martensitic transformation and can be analyzed within the frame work of the martensitic transformation. The lattice shear deformation is accomplished by a high density of screw dislocations in the transformed laths. Such screw dislocations can be introduced by cold rolling.The hydrogen absorption/desorption properties of other intermetallic materials may be expected to be improved similarly to Ti_3Al-base alloys. Thus, the hydrogen absorption and desorption of Mg-Ca-Ni alloys, which absorb hydrogen easily and form a very stable hydride, was investigated. However, we have not succeeded in enhancing their hydrogen absorption and desorption properties yet. Further work is needed to clarify the reason for this.

通过压力组分等温度测量值和显微镜观测，在接受热处理和冷滚动的样品吸收氢之前和之后，研究了TI_3AL碱合金中可逆的氢吸收和脱附的机制。 Ti_3Al碱合金中的α-氢氢化物到β-氢相变的变化是在非常低的压力下发生的，在正常条件下是可逆的。但是，如果对样品进行热处理，则可以使β和伽马氢化物之间的转化可逆，从而使其在其微观结构中包含O期或通过冷滚动适当变形。在TI_2NBAL附近具有组成的三种TI-AT-NB合金中，证明了O期对氢吸收/解吸的有益作用。发现有益效应与O期的结构和应变场有关，而不是O期和基质之间的界面。当它们轻微变形时，它们的氢吸收和解吸特性将得到改善。微观结构观察表明，β和伽马氢化物转化的发生方式与马氏体转化非常相似，可以在马氏体转化的框架工作中进行分析。晶格剪切变形是通过转换后板条中的高密度螺钉位错来实现的。可以通过冷滚动引入此类螺钉位错。预计其他金属间材料的氢吸收/解吸特性将与Ti_3Al碱合金相似。因此，研究了MG-CA-NI合金的氢吸收和解吸，这些合金容易吸收并形成非常稳定的氢化物。但是，我们尚未成功增强其氢的吸收和解吸特性。需要进一步的工作来阐明这样做的原因。