Visualized understanding and engineering of directional atomic bonding -Using the conventional shear -synchroshear transition in silicides with the C40 structure as a vehicle -

定向原子键合的可视化理解和工程 -使用硅化物中传统的剪切-同步剪切转变，以 C40 结构作为载体 -

基本信息

批准号：
10450260
负责人：
YAMAGUCHI Masaharu
金额：
$ 9.02万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 1999
项目状态：
已结题

项目摘要

Transition metal disilicides, in particular those formed with refractory metals of groups IVa 〜 VIa in the Periodic Table have drawn considerable attention for structural applications at high temperatures because of their high melting temperature, intrinsic oxidation resistance, resistance, relatively low density and high thermal conductivity. These transition metal disilicides, except ZrSiィイD22ィエD2 and HfSiィイD22ィエD2 with the C49 structure, crystallize into one of the three structures of the types C11b, C40 and C54, which are all relatively simple and closely akin to each other. The relative phase stability of these three structures is closely related with the nature of directional atomic bonding in these structures. The deformation mechanism of transition metal disilicides with these structures was studied putting stress on the effect of atomic bonding on their deformation.Transition metal disilicides with the three crystal structures were found to be classified into two *oups, i.e. one group including CrSiィイD22ィエD2 whose plastic flow is observed only above 700℃. The difference in deformability between the two groups of silicides is closely associated with the difference in the core structure of dislocations.The creep behavior and creep strength of MoSiィイD22ィエD2 alloyed with Nb, W, Re and A1 was also studied in the temperature range from 1200 to 1400℃. The creep strain rate for the [001] orientation, which is the hardest orientation in conventional compression tests, is significantly improved upon alloying with Re, Nb, W and A1. The extent of improvement is significantly large for adding Re and Nb. The creep rate attained for Re-bearing MoSiィイD22ィエD2 is comparable to that obtained for the most advanced SiィイD23ィエD2 NィイD24ィエD2-based composites in tension.

过渡金属二硅化物，特别是由周期表中IVa〜VIa族难熔金属形成的过渡金属二硅化物，由于其高熔化温度、固有的抗氧化性、电阻、相对低的密度和高导热性，在高温结构应用中引起了广泛的关注。这些过渡金属二硅化物，除了具有C49结构的ZrSiD22D2和HfSiD22D2外，均结晶成三种结构之一。 C11b、C40和C54类型的过渡金属二硅化物都相对简单且彼此非常相似，这三种结构的相对相稳定性与这些结构中的定向原子键合的性质密切相关。研究了这些结构，重点关注原子键对其变形的影响。发现具有三种晶体结构的过渡金属二硅化物可分为两个*组，即一组包括CrSiD22D2仅在700℃以上才观察到塑性流动。两组硅化物变形能力的差异与位错核心结构的差异密切相关。Nb、W、Re合金化MoSi D22的蠕变行为和蠕变强度。还研究了A1在1200~1400℃温度范围内的[001]蠕变应变率。取向是传统压缩试验中最硬的取向，在与 Re、Nb、W 和 A1 合金化后得到显着改善。添加 Re 和 Nb 后，改善程度显着较大。含 Re 轴承的 MoSi D22D2 获得的蠕变速率为：与最先进的 SiD23D2 基复合材料在拉伸时获得的结果相当。