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Development of Cr_2Nb Intermetallic Compounds with High Fracture Toughness as Ultra High Temperature Structural Materials

高断裂韧性Cr_2Nb金属间化合物超高温结构材料的研制

基本信息

批准号：
07555495
负责人：
TAKASUGI Takayuki
金额：
$ 0.32万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07555495/
关键词：
Intermetallic compound Laves alloy Fracture toughness Ultra high temperature structural materials Cr_2Nb Alloy design

项目摘要

In this study, to develop the Cr_2Nb intermetallics which can be used at 1473K and the enough fracture toughness at ambient temperature, the mechanical properties of the alloys prepared by alloy design, microstructural control and advanced process were investigated. The following results were obtained.1) Structures of Cr_2Nb Laves alloy were observed by x'-ray and (HR) TEM.High temperature compressive deformation behavior was investigated, and discussed in correlation with the activated dislocation structures. Consequently, the deformation begins at 1473K,and accomplished by an activation of the Schockley partials of 1/2 <011> dislocations, or the dynamic recrystallization.2) The isothermal phase diagrams of Cr-Nb-V,Cr-Nb-Mo and Cr-Nb-W ternary alloy systems at 1623K were clarified. It was shown that the C15 Cr_2Nb Laves phases are directly equilibrated with bcc solid solution without forming any ternary intermediate compounds.The effect of ternary alloying elements such as V,Mo, W and Ti on the alloying behavior, the lattice properties and the phase stability of the C15 Cr_2Nb was investigated. It was shown that the solubility of V and W are more than 10at%, that of W is about 5at%, and Ti forms the continuous solid solution range toward to Cr_2Ti. The ALCHEMI determined that V occupies the sublattice of Cr, Mo, Ti and W do the sublattices of Nb. Also, TEM observation on the microstructure of the alloys with ternary elements suggested that V enhance the stability of C15 structure but Mo, W and Ti reduce the stability of the C15 structure.4) The mechanical properties of the ternary alloys consisting of the Cr_2Nb and the bcc solid solution were investigated by compression test in a wide range of test temperature. High fracture toughness at low temperature was observed on the alloys consisting of the C15 phase and Cr-rich bcc solid solution, while high strength at high temperature was observed on the alloys consisting of the C15 phase and Nb-rich bcc solid solution.

本研究以开发能在1473 K下使用并在室温下具有足够断裂韧性的Cr_2Nb金属间化合物为目标，通过合金设计、组织控制和先进工艺制备了Cr_2Nb合金，并对其力学性能进行了研究。1）用X射线衍射和高分辨透射电镜观察了Cr_2Nb Laves合金的组织结构，研究了合金的高温压缩变形行为，并与激活位错结构进行了讨论。结果表明，变形开始于1473 K，并通过激活1/2位错的Schockley偏分<011>或动态再结晶完成。2）绘制了Cr-Nb-V、Cr-Nb-Mo和Cr-Nb-W三元合金系1623 K等温相图。结果表明，C15 Cr_2Nb Laves相直接与体心立方固溶体相平衡，没有形成任何三元中间化合物，研究了V、Mo、W和Ti等三元合金化元素对C15 Cr_2Nb合金化行为、晶格性质和相稳定性的影响。结果表明，V和W的固溶度均大于10at%，W的固溶度约为5at%，Ti向Cr_2Ti方向形成连续固溶区。ALCHEMI确定V占据Cr、Mo、Ti和W的亚晶格而不占据Nb的亚晶格。TEM观察表明，V提高了C15组织的稳定性，而Mo、W和Ti则降低了C15组织的稳定性。4）在较宽温度范围内，通过压缩试验研究了Cr_2Nb和bcc固溶体组成的三元合金的力学性能。由C15相和富Cr bcc固溶体组成的合金具有较高的低温断裂韧性，而由C15相和富Nb bcc固溶体组成的合金具有较高的高温强度。