Anomalous Plasticity in MoSi_2 Single Crystals and its utilization

MoSi_2单晶的反常塑性及其利用

基本信息

批准号：
07405031
负责人：
YAMAGUCHI Masaharu
金额：
$ 22.02万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1997
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07405031/
关键词：
Transition metal silicides MoSi_2 Deformability Deformation modes Critical resolved shear stress Deformation mechanism Stacking fault Synchro shear WSi_2 (Mo.W)Si_2 単結晶変形降伏応力転位方位依存性転位分解

项目摘要

IN 1995 we first reported that plastic flow is possible even at temperatures as low as room temperature for single crystals of MoSi_2 wirh orientations away from[001], while single crystals with orientations near [001] can be plastically deformed on a macroscopic scale only at temperatures above 1300ﾟC.In this study, we first examined whether such anomalous plasticity oberved in MoSi_2 single crystals with orientations away from [001] is observed in other transition metal disilisides with the C11_b structure such as WSi_2 and (Mo, W) Si_2, those with the C40 structure such as Mo(Al, Si)_2, VSi_2, NbSi_2, TaSi_2 and CrSi_2, TiSi_2 with the C54 structure. Secondly, we investigated possible ways to utilize the anomalous plasticity for structural spplications of MoSi_2.Deformation experiments of four different C40 disilicides result in the following findings : (1) plastic flow of VSi_2, NbSi_2 and TaSi_2 is possible only when slip along <1210> on (0001) is operative and no other slip systems are observed in the whole temperature range investigates, (2) basal slip in VSi_2, NbSi_2 and TaSi_2 occurs in a conventional manner unlike in CrSi_2 and Mo (Si, Al)_2 in which the corresponding slip occurs through a synchroshear mechanism, (3) while the onset temperature for plastic flow in NbSi_2 is 500ﾟC for as-grown crystals, it is lowered by 300ﾟC when the crystal is prestrained at 1400ﾟC and then re-deformed at low temperatures, (4) the critical resolved shear stress (CRSS) for basal slip in NbSi_2 decreases with increasing temperature, but exhibits a moderate peak around 1300ﾟC.One way to utilize the anomalous plasticity of MoSi_2 is to form MoSi_2-base composites with NbSi_2 and TaSi_2 forming interfaces perpendicular to cleavage planes in MoSi_2.

1995年，我们首次报道，远离[001]取向的MoSi_2单晶即使在低至室温的温度下也可能发生塑性流动，而接近[001]取向的单晶只能在宏观尺度上发生塑性变形。温度高于1300°C。在这项研究中，我们首先检查了在取向远离的MoSi_2单晶中是否观察到这种反常塑性。 [001] 观察到其他具有C11_b结构的过渡金属二硅化物如WSi_2和(Mo,W)Si_2，具有C40结构的如Mo(Al,Si)_2、VSi_2、NbSi_2、TaSi_2和CrSi_2、TiSi_2其次，我们研究了利用异常可塑性进行结构应用的可能方法。 MoSi_2.四种不同C40二硅化物的变形实验得出以下结果：（1）只有当沿（0001）上的<1210>滑移起作用并且在该区域中没有观察到其他滑移系统时，VSi_2、NbSi_2和TaSi_2的塑性流动才可能发生。在整个温度范围内进行研究，（2）VSi_2、NbSi_2和TaSi_2中的基底滑移以常规方式发生，这与CrSi_2和Mo不同(Si, Al)_2，其中相应的滑移通过同步剪切机制发生，(3) NbSi_2 中生长晶体的塑性流动起始温度为 500°C，而当晶体生长时，塑性流动起始温度降低了 300°C。在1400°C预应变，然后在低温下重新变形，(4)NbSi_2基底滑移的临界分辨剪切应力(CRSS)降低随着温度的升高，在1300℃左右出现一个中等峰值。利用MoSi_2的反常塑性的一种方法是形成MoSi_2基复合材料，其中NbSi_2和TaSi_2形成垂直于MoSi_2解理面的界面。