Processing, Microstructure and Creep Behaviour of Mo-Si-B-Based Intermetallic Alloy for Very High Temperature Structural Applications. (Annual Report, July 1, 2004-June 30, 2005)

摘要

This research project is concerned with developing a fundamental understanding of the effects of processing and microstructure on the creep behavior of refractory inter-metallic alloys based on the Mo-Si-B system. During this year, the compressive creep behavior of a Mo-3Si-1B (in wt.%) alloy at 1100 and 1200 degrees C were studied and related to the deformation mechanisms through electron microscopy observations of microstructural changes and deformation structures. The microstructure of this alloy was three-phase, being composed of -Mo, Mo3Si and T2-Mo5SiB2 phases. Results of compressive creep tests at 1200 and 1100 degrees C showed that the creep rates were quite high at stress levels between 250 and 500 MPa, Two minima in the creep strain rate versus strain data were noted, one at small strain values and the second at much larger strains.