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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，特别是与周期表中IVa族至VIa族的难熔金属形成的那些，由于其高熔融温度、固有抗氧化性、电阻、相对低的密度和高导热性，在高温下的结构应用中引起了相当大的关注。这些过渡金属二硅化物，除了具有C49结构的ZrSi D22 D2和HfSi D22 D2之外，结晶成C11 b、C40和C54类型的三种结构中的一种，它们都相对简单并且彼此非常相似。这三种结构的相对相稳定性与这些结构中原子的定向成键性质密切相关。研究了这三种晶体结构的过渡金属二硅化物的变形机制，着重分析了原子成键对其变形的影响，发现这三种晶体结构的过渡金属二硅化物可分为两类：一类是CrSi_xD_22_xD_2，其塑性流动仅在700℃以上观察到;本文还研究了Nb、W、Re和Al合金化的MoSi合金化D22合金化D2在1200 ~ 1400℃温度范围内的蠕变行为和蠕变强度。[001]取向的蠕变应变速率，这是在传统的压缩试验中最硬的取向，显着改善后与Re，Nb，W和Al合金化。对于添加Re和Nb，改善的程度显著大。在拉伸条件下，含Re的MoSi合金D22合金D2的蠕变速率与最先进的Si合金D23合金D2 N合金D24合金D2基复合材料的蠕变速率相当。