Ternary Phase Equilibria in Transition Metal- Boron-Carbon-Silicon Systems. Part III. Special Experimental Techniques. Volume I. High Temperature Differential Thermal Analysis.

摘要

A high sensitivity differential thermal analysis apparatus, capable of operating to temperatures of 3600 C under controlled time-temperature conditions, is described. Measurements on binary and ternary carbide systems revealed a number of previously undetected phase reactions. Wth the exception of V2C, all subcarbides of the refractory transition metals undergo isothermal phase changes at high temperatures. The lower temperature stability limits of the high temperature phases in the systems Mo-C and W-C were determined. Similar to the corresponding system with oxygen, the a-modification of hafnium is stabilized to higher temperatures by carbon additions, while the alpha-beta- transformation in titanium and zirconium is affected to a moderate extent only. The application of DTA-techniques to the investigation of non-variant equilibria involving a liquid phase and to the study of reaction kinetics (disproportionation of solid solutions, reactions along non-equilibrium paths, reactions involving order-disorder phenomena) is discussed and examples are given. (Author).