INFLUENCE OF NICKEL ON THE PHASE COMPOSITION, HARDENING, AND CASTING PROPERTIES OF ALUMINUM ALLOY Ats4Mg

摘要

1. The influence of nickel on the structure and phase composition of the alloy Al-4 percent Zn--1.5 percent Mg was studied. Nonequilibrium and equilibrium poly thermal sections Al--4 percent Zn--1.5 percent Mg--Ni were constructed, fromwhich it follows that the minimal crystallization interval corresponds to a nickel concentration ~ 4 percent, since with this concentration the composition of the alloy is close to the eutectic. Addition of Ni in these quantities leads to animprovement' in the indicator of hot brittleness which is most likely associated with contraction of the crystallization interval. The solldus interval remains at a high level (> 600 deg C), which makes it possible to conduct high-temperature annealing for the purpose of obtaining globular inclusions of Al_3Ni phase. 2. It is shown that addition of 4 percent Ni to the base alloy substantially improves the strength properties (the yield point increases by ~45 percent and the tensile strength, by ~25 percent). Meanwhile, ductility falls slightly. The increase in the alloying capability of the aluminum matrix (cf. Table 2) and the contribution of the particles of nickel aluminide of eutectic origin are the most likely causes of hardening. 3. It is shown that addition of 4 percent Ni to the base alloy substantially improves the strength properties (the yield strength increases by ~45 percent, ultimate breaking strength by ~25 percent). Ductility meanwhile falls slightly. An increase in the alloyability of the aluminum matrix (cf. Table 2) and the contribution of particles of nickel aluminide of eutectic origin are the most probable causes of the hardening.