Effects of B Additions on the Intragranular and Cellular Precipitations in a Cu–Be Alloy

Abstract

Effects of B additions on the intragranular and cellular precipitations in a Cu-2 mass% Be alloy on aging at 523 and 623 K after quenching from 1093 K were investigated by means of hardness measurements, optical and electron microscopic observations, and X-ray analysis. The addition of 0.02–0.1 mass% B suppressed the formation of G.P. zones and retarded the precipitation of γ′ phase. The lattice parameter of the α solid solution of the B-added alloy increased with B addition. This result suggests that B atoms exist interstitially in the α solid solution and suppress the formation of G.P. zones and retard the precipitation of γ′ phase as a result of the strong interaction with vacancies. The formation and growth of grain boundary cells were suppressed by the addition of 0.02–0.05% B, but promoted by excess additions of B, 0.1%.