Crack initiation in the zinc–mercury embrittlement couple

Publisher Website
Google Scholar
Abstract
For truly brittle crack initiation—in which the crack initiation energy is less than or equal to the true surface energy of the fracture plane—it can be shown that where σFA−B is the fracture stress of coarse-grained specimens of solid metal A when exposed to liquid metal B; σfA is the flow stress of specimens of metal A when tested in an inert environment; and ηIA−B , the coefficient of embrittlement for crack initiation for the couple A-B, is defined as the ratio of the energies required to separate atoms across the fracture plane of metal A in the presence and absence of embrittling liquid metal B. Using this relationship in conjunction with studies of the flow and fracture behaviour of polycrystalline zinc of various grain sizes tested in the amalgamated and unamalgamated conditions, ηIZn−Hg was found to be 0·60 ±0·04 at 298°k. This value is identical with the coefficient of embrittlement for cleavage crack propagation, ηPZn−Hg , previously determined for this couple—probably because in zinc, both crack initiation and propagation occur in the same atomic plane. The limitations and possible practical application of coefficients of embrittlement are briefly discussed.

This publication has 13 references indexed in Scilit: