Microstructure and temperature dependence of the microhardness of W-4V-1La₂O₃ and W-4Ti-1La₂O₃

Abstract

W–4V–1La₂O₃ and W–4Ti–1La₂O₃ (wt.%) alloys have been produced by mechanical alloying and subsequent hot isostatic pressing. Electron microscopy observations revealed that these alloys exhibit a submicron grain structure with a dispersion of La oxide nanoparticles. Large V or Ti pools with martensitic characteristics are found segregated in the interstices between the W particles of the respective alloys. Microhardness tests were carried out over the temperature range 300–1073 K in vacuum. The microhardness–temperature curve for W–4V–1La₂O₃ exhibited the expected decreasing trend with increasing temperature although the microhardness stayed constant between ~473 and 773 K. The W–4Ti–1La₂O₃ presented quite different temperature dependence with an anomalous microhardness increase for temperatures above ~473 K.