Molybdenum Silicide (MoSi2) Based High Temperature Materialswith Enhanced Ductility and Toughness

硅化钼(MoSi2)基单片和复合材料在1000-1600oC温度范围内具有潜在的航空应用前景。由于MoSi2基金属间化合物具有极高的脆性，已被证明是一种非常难加工的材料。为了成功地加工和制造基于MoSi2的部件，有必要提高其低温塑性和韧性。本研究致力于通过先进的快速凝固和粉末冶金工艺制备细晶MoSi2，以提高其低温塑性和韧性。细小的晶粒度将减小滑移长度，从而降低晶界的应力集中，从而提高塑性。第一阶段的研究还将调查TiB2和HFC分散体对晶粒细化的影响。预计这些稳定的分散体将保留这些非共格粒子周围的精细微结构和空隙，特别是在高温下。第二阶段的研究将更详细地研究弥散体/晶界和弥散体/位错的相互作用，以确定工艺-显微组织-力学性能之间的关系，从而在室温和高温下都能获得最佳的力学性能。

Molybdenum silicide (MoSi2) based monolithic and composite materials have potential aircraft applications in the temperature range 1000-1600oC. MoSi2 based intermetallics have proven to be rather formidable materials to process because of its extreme brittleness. In order to successfully process and fabricate components based on MoSi2, it is necessary to enhance its low temperature ductility and toughness. This research focusses on preparation of fine grained MoSi2 via advanced rapid solidification and powder metallurgical processing to improve its low temperature ductility and toughness. The fine grain size will reduce the slip length, therefore, lower the stress concentration at the grain boundaries and thus enhance ductility. Phase I research will also investigate the effect of TiB2 and HfC dispersoids on grain refinement. It is expected that these stable dispersoids will retain the fine microstructure as well as voids around these incoherent particles, especially at high temperatures. Phase II research will investigate in more detail the dispersoid/grain boundary and dispersoid/dislocation interactions to define the processing-microstructure-mechanical property relationships so that optimum mechanical properties will be attained at both room and elevated temperatures.