Mechanical and Fatigue Properties of Tungsten Heavy Alloy Prepared by RF-Plasma

Ondřej KovářÍk, Jaroslav Čech, Jan Cizek, Jakub Klečka, Michal Hajíček, F. Azarmi, X. Chen, J. Cizek, C. Cojocaru, B. Jodoin, H. Koivuluoto, Y.C. Lau (+4 others)
2021 Thermal Spray 2021: Proceedings from the International Thermal Spray Conference   unpublished
Tungsten heavy alloy (WHA) of W-Ni composition was deposited from a blend of standard thermal spray powders using radio frequency inductively coupled plasma torch (RF-ICP) in a protective atmosphere. The deposit (RF WHA) contained a fully developed WHA structure; i.e.; spherical W particles embedded in a Ni-rich matrix. The bending tensile strength Rm; bending yield strength Rp;0.2; and elastic modulus of the deposit were compared with two W-Ni-Co references fabricated by powder metallurgy (PM
more » ... HA) via sintered and quenched (PMSQ); and forged and annealed (PM-FA). While the RF deposit properties are comparable with the PM-SQ reference; the PMFA exhibited higher mechanical properties. The deposit showed very limited ductility A < 3%. The fatigue crack growth rate in the deposit measured in bending (R < -1) was comparable to the PM-SQ reference material in the near-threshold region whereas the forged PM-FA had significantly better fatigue performance. In the near-threshold fatigue regime; the crack growth took place in the Ni-rich matrix. In the Paris regime; the similar fracture mode was observed; with the exception of PM-SQ; where the tungsten particles fracture contributed significantly. The static failure was exclusively trans-particle in RF WHA; while both PM WHAs failed by a mix of ductile matrix failure and trans-particle cleavage fracture. The fracture toughness of the deposit was significantly lower than the references. These early results indicate that RF-plasma spray is a suitable and efficient manufacturing method for production of WHA materials; however with limited mechanical properties in some aspects.
doi:10.31399/asm.cp.itsc2021p0115 fatcat:3xkh6zfx2za4tjmy3sqaeay4pi