La, Pr, Nd microalloying influence on deformable heat resisting nickel alloy of the VZh175 type structure forming

Abstract

By high-allowing metal physical and heat physical techniques complex means lanthanum, prazeodim and neodim separate influence on deformable high-heat resisting Ni-Co-Cr-Al-Ti-W-Mo-Nb alloying system nickel base alloy structure forming features are investigated. Three model material compositions structural and phase conditions were studied after heat treatment. It is shown that lanthanum, prazeodim and neodim individual influence on quantity of phases, grain and interphase boundaries structure change and material heat physical characteristics variously. These alloys class structure represents gamma?- solid solution grains with primary gamma?-phase particles, evenly distributed on grain boundaries. The alloy contains niobium and titanium based carbides MC, being formed at material crystallization stage during melting. Solid solution in grains is strengthened by secondary gamma?-phase particles. Grain boundaries are strengthened by gamma?-phase, chrome and molybdenum based carbides and borides particles. At introduction in the material rare earth elements (RZE) complicated structure different sizes and morphology nickel and RZE based intermetallid phases, which are evenly distributed in material volume, are formed. They also allocated on grain and gamma/gamma? interphase boundaries, in addition strengthening them. Material structure change distinctions are revealed: maximum quantity grain and gamma/gamma? interphase boundaries secondary carbides, borides and intermetallid phases with RZE after heat treatment are containing at composition with the prazeodim; composition with the neodim differs by the maximum nanodimensional gamma?-phase quantity and the minimum secondary intermetallid phase with RZE quantity. Containing lanthanum, prazeodim and neodim compositions differ with temperature and total warmth of endothermic effect of carbide, boride and intermetallic phases dissolution.