Embrittlement of Cu[100] symmetric tilt boundaries induced by Sb segregation

To investigate the misorientation dependence of fracture behavior and Sb segregation level for different [001] symmetric tilt boundaries in Cu-2.0 mass% Sb alloy bicrystals tensile tests at several temperatures from 77 to 743 K an energy-dispersed X-ray spectroscopy analyses were performed. The degree of embrittlement of grain boundaries becomes weaker as the test temperature increases up to about 400 K, while it becomes stronger again at higher temperatures. The fracture stress at 77 K and Sb segregation level vs. misorientation angle curves display several peaks and cusps at the same angles, and the positions of these peaks and cusps are in agreement with those of cusps in the boundary energy of pure Cu vs. misorientation curve. Grain boundaries with higher energy are more sensitive to Sb segregation to cause grain-boundary embrittlement.