Effect on Nanoindentation in La2O3-reinforced W and W–V alloys produced by hot isostatic pressing
September 29-October 4, 2019
W is a principal candidate material for fabricating plasma facing components (PFC) in a future fusion power reactor due to its high melting temperature, good thermal conductivity, thermal stress resistance, low tritium retention and high temperature strength . For these applications, the structural materials should have an operating temperature window 873-1600 K and a ductile brittle transition temperature (DBTT) in the interval 573-673 K, as well as a recrystallization temperature (RT) above1600 K . La2O3 dispersion or Al, K, Si doping can improve the mechanical strength and increase the tungsten RT, although the DBTT appears not to be lowered . Most of these W alloys were prepared by powder metallurgy methods, in particular by ball milling and subsequent pressure less sintering or hot isostatic pressing (HIP) . Recently, W and WTi alloys reinforced with Y2O3 have been sintered by HIP . The use of Ti as sintering activator and the Y2O3 dispersion result in full dense materials exhibiting improved mechanical properties and oxidation resistance . However, the Y2O3 particles in a W matrix appear to be unstable at temperatures above 1600 K becoming into coarse particles of complex W-Y and W-Y-Ti oxides, which could worsen the mechanical properties. This drawback may be avoided if V is used as sintering activator. The V-W system exhibits an isomorphous phase diagram with a continuous range of solid solution .
The aim of the present work is to produce W and W-V alloys reinforced with La2O3 particles and investigate their microstructure and thermal stability in order to obtain a structural material with favor able properties to be used for developing PFC. W and W-V alloys reinforced with La2O3 particles have been produced by MA and subsequent HIP at 1573 K and 195 MPa. The microstructure of the consolidated alloys has been characterized by scanning electron microscopy, energy dispersive spectroscopy analyses and X-ray diffraction. The mechanical properties were studied by nanoindentation measurements. The results show that practically full dense billets of W-V, W-V-La2O3 and W-La2O3 alloys can be produced. The microstructure analysis has shown that islands of V are present in W V and W V-1La2O3 alloys. In W-1La2O3 islands of La2O3 are also present. The nanohardness of the W matrix increases with the addition of V, while decreases with the addition of La2O3.
 Davis JW, Barabash VR, Makhankov A, Plöchl L, Slattery KT. Assessment of tungsten for use in the ITER plasma facing components. J Nucl Mater 1998;258–263: 308–12.
 Bolt H, Barabash V, Krauss W, Linke J, Neu R, Suzuki S, et al. Materials for the plasma-facing components of fusion reactors. J Nucl Mater 2004;329–333:66–73.
 M. Rieth, B. Dafferner, J. Nucl. Mater. 342 (2005) 20.
 M.A. Monge, M.A. Auger, T. Leguey, Y. Ortega, L. Bolzoni, E. Gordo, R. Pareja, J. Nucl. Mater. 386–388 (2009) 613.
 M.V. Aguirre, A. Martín, J.Y. Pastor, J. LLorca, M.A. Monge, R. Pareja, Metall. Mater. Trans. 40A (2009) 2283–2290.
 S.V. Nagender Naidu, A.M. Sriramamurthy, M. Vijayakumar, P. Rama Rao, in: J.F. Smith (Ed.), Phase Diagrams of Vanadium Alloys, Monograph Series on Alloy Phase Diagrams, ASM International, Metal Parks, Ohio, 1989, p. 313.
Javier Martínez-Gómez, Begoña Savoini, and Ramiro Pareja, "Effect on Nanoindentation in La2O3-reinforced W and W–V alloys produced by hot isostatic pressing" in "Nanomechanical Testing in Materials Research and Development VII", Jon Molina-Aldareguia, IMDEA-Materials Institute, Spain Eds, ECI Symposium Series, (2019). https://dc.engconfintl.org/nanochemtest_vii/6