Research on the Copper-Rich Solid Solution in Cu-Mn Binary System. I

The authors investigated the alloys in Cu-Mn system containing manganese up to 61.3% from various stand points, namely, microstructures, hardness changes due to various heat-treatments, temperature dependence of electric resistivity and thermal expansion, and density at room temperature. The most outstanding results were as follows : (1) The solubility curve of this system was similar to that proposed by Grube with a slight difference in the range of lower concentration, but did not agree with that reported by Ishiwara and Isobe. (2) The alloy with about 10% of manganese displayed some anomalies in higher temperature range, although it was conceived to be homogeneous solid solution. Furthermore, in the alloys of higher concentration a singular process of a certain transformation type is supposed to have existed, regardless of the solubility change. (3) The activation energy of hardening for the alloy containing 42.9% of manganese quenched from 750℃ and aged at 400°?550℃ was about 23, 600 cal/mol, but it was very small for the alloy of 61.3% of manganese