EMBRITTLEMENT OF Cu-Zn ALLOYS IN THE SOLIDIFICATION PROCESS.

Tensile strength and apparent deformation of solidifying binary Cu-Zn castings were studied at various fractions of solid by use of a tensile test apparatus newly developed. The alloys complete solidification through four stages with increase in fraction of solid. The alloys at stage I with fractions of solid up to f//a have significant deformation. Those at stage II with fractions of solid f//a to f//b rapidly lower the deformation. Those at stage III with fractions of solid f//b to f//c minimize the and and have noticeable strength. Those at stage IV with fraction of solid f//c or more show rapid increase of both deformation and strength (f//a less than f//b less than f//c). The alpha -phase solid solution alloys containing Zn up to 30% have less deformation in the extended brittle stage III that the beta -phase solid solution alloys containing Zn 40 to 45%.