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Thermal stability of the grain structure in the W-2V and W-2V-0.5Y <inf>2</inf>O<inf>3</inf> alloys produced by hot isostatic pressing

Abstract:

W-2V and ODS W-2V-0.5Y2O3 alloys have been produced following a powder metallurgy route consisting of mechanical alloying and a subsequent high isostatic pressing HIP at 1573 K. The grain microstructure and microhardness recovery of the alloys have been studied in samples subjected to isothermal treatments in vacuum in temperature range 1073-1973 K. Both alloys exhibit a duplex grain size distribution consisting of a submicron-sized grain and a coarse-grained population. It has been found that the Y2O 3 addition inhibits growth of the coarse grains at T < 1973 K. Submicron grain growth, with activation enthalpy of 1.9 and 2.49 eV for W-2V and W-2V-0.5Y2O3, respectively, was observed at T ≥ 1573 K. It resulted that the rate constant for grain growth is 30 times higher in W-2V-0.5Y2O3 than in W-2V. The considerable enhancement of the microhardness in the W-2V-0.5Y2O3 appears to be associated to dispersion strengthening. © 2013 Elsevier B.V.