1290 / 2019-10-31 11:31:56

Microstructural analysis on the multi-component system alloy formed at the bonding interface of dissimilar-metals joint of V-base and Ni-base alloys

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Hardness and corresponding microstructure at the interface between V-4Cr-4Ti and Hastelloy alloy after explosive welding (EXW) were studied. Typical wavy interface was characterized after EXW. Discontinuous eddy regions at the interface in which obvious hardening up to 691~870 VHN was observed. Microstructural observations indicated that the eddy region comprised Ni37.1V21Cr19.6Fe14.4M04.4TiCo0.6 with a fcc structure and dislocations, and without any precipitates. Based on the composition, the entropy of mixing, ΔSmix, is 12.66 J K-1 mol-1 and Ω, defined as Tm ΔSmix / ΔHmix, is 1.9, where Tm and ΔHmix are estimated melting point, 1948 K, and the enthalpy of mixing, -12.39 kJ mol-1, respectively. These values mean that stabilized solid-solution without any intermetallics precipitation is possible. The dislocation density is 3.4×1015/m2 which indicated working hardening. Thus, the obvious hardening in eddy region is attributed to solid solution hardening and work hardening in multi-component high entropy alloy.