Abstract
The phenomenon and mechanism of high-temperature embrittleness in Cu-Cr alloy were studied. Commercially available Cu-1.0%Cr alloys solution annealed, quenched, or subsequently cold-worked were aged at various temperatures up to 700°C. These specimens were tensile-tested in the temperature range as above. As for the mechanism, the microstructures of tensile-strained or fractured specimens were mainly examined by means of optical and electron microscopy, EPMA, etc.
The results obtained were as follows: (1) The alloy except in the over-aged state always showed marked embrittleness at about 500°C. (2) Although the phenomenon was associated with intergranular fracture, any abnormality at or near grain boundaries was never detected. (3) It was suggested from the microstructural studies that the embrittleness was due to (i) the high stress concentration at the grain boundaries caused by blocking of the slip bands and (ii) the decrease in strength of the grain boundaries with rising temperatures.
