MICROSTRUCTURE AND AGE HARDENING IN RAPIDLY SOLIDIFIED Mo ALLOYS

The spin ribbons and splat foils of various Mo-base alloys were made by the arc melt-spinning and hammer-anvil techniques. The mechenical properties, surface topography and microstructure have been studied. A strong grain refinement and an age hardening response have been observed in the as-quenched and annealed specimens, respectively. The precipitates which are responsible for age hardening were identified to be Mo_2B(C16, BCT) in Mo-B alloys and Mo_2B and more stable ZrB_2(A_3) in Mo-Zr-B alloys. The alloys in which the borides are as strengthening phases possess very high strength and hardness, indicating the prospect of developing high strength Mo-base alloys by rapidly solidified techniques.