Microstructural evolution, textural evolution and thermal stabilities of W and W – 1 wt% La2O3 subjected to high-pressure torsion

Abstract

Ultra-fine grained W and nanocrystalline W – 1 wt% La2O3 (WL10) were successfully fabricated by unconstrained high-pressure torsion at 400 °C. Torsion torque, microstructural evolution, and textural evolution of W and WL10 along torsion revolution were systematically evaluated for the first time. Their deformation mechanisms during high-pressure torsion were proposed. Results show that both materials exhibited work-hardening and geometric dynamic recrystallization during high-pressure torsion. The existence of La2O3 particles caused discontinuous dynamic recrystallization in WL10 and formed γ-fiber texture. The evolution of γ-fiber texture in WL10 along with torsion strain was analyzed as well. The existence of La2O3 particles leaded to dispersion-hardening in WL10 at large strain levels when those particles were sufficiently refined. Deformation inhomogeneity occurred in W at ultrahigh strain levels accompanied by coarsening microstructure. In addition, the as-deformed ultra-fine grained W and nanocrystalline WL10 exhibited marked thermal stability at 1000 °C up to 6 h.