Influence of alloying elements on the intragranular precipitation (G. P. Zone formation )in Cu-Be alloy

摘要

A Cu- l2at % Be alloy is hardened in two stages by the formation of G. P. zone, γ" phase and γ'phase (CuBe') in the matrix on aging at 523 K after quenching from 1093 K. The first and secondstages of hardenig are caused mainly by the formation of G. P. zone and the precipitation of γ'phase, respectively. In this study, effects of 13 kinds of micro alloying elements (Zr, Pb, Bi, Cd, Ti,Cr,Fe, Co, In, Al, Ni, Zn and Mn) on the first stage of hardening of the alloy were investigated in relationwith solid solubilities of these elements to the solvent Cu. The addition of Pb, Bi and Zr elements,which are scarcely soluble Cu, suppressed remarkably the formation of G. P. zone. On the otherhand,the addition of Ni and Mn, which are fully soluble to Cu, scarcely affected the formation of G. P.zone. Thus, it is clarified that the elements having smaller solid solubility to Cu suppressed morestrongly the formation of the G. P. zone.The reason is explained by the mechanism that the elements having small solid solubility to Cusegregate at grain boundaries and around vacancies in the matrix, and trap the vacancies, which areneeded for the migration of Be atoms to {100} planes of the matrix.