Effects of Surface Finishing Conditions and Alloying Elements on the Structure of an Iron Molybdenum Boride Base Hard Alloy

Abstract

A recently developed iron molybdenum boride base hard alloy has good mechanical properties, excellent wear and corrosion resistance. This hard alloy produced by liquid phase sintering consists of a hard phase composed mainly of a Mo₂FeB₂ type complex boride and an iron base, stainless steel-like binder phase.
In the present investigation, both the effects of surface finishing condition on the binder phase and the effects of alloying elements on the structure and alloy partitioning were studied by X-ray diffractometry, Auger analysis, transmission electron microscopy, etc.
Results indicate that the binder phase of the alloy becomes martensitic or austenitic depending on the alloy composition and sintering conditions, and that sometimes the martensitic transformation of the austenite in the binder phase is induced by surface grinding.
This hard alloy contains the Fe₂B or M₆C (M : metal) phases depending on the composition in addition to the Mo₂FeB₂ type complex boride and an iron base binder phase.
A martensitic binder of the alloy seems to give higher transverse rupture strength and hardness than an austenitic binder.