Abstract
The authors investigated the alloys containing up to 61.3% of Mn from various stand-points, namely, microstructures, hardness changes under various heat-treatments, temperature dependence of electric resistvity and thermal expansion, and density at room temperature. Most outstanding results were as follows:
(1) The solubility curve of this system showed the form similar to that proposed by Grube but with a slight difference from it in the range of lower concentration, and did not agree with the type reported by Ishihara & Isobe.
(2) The alloy with about 10% of Mn displayed some anomalies at the 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 was supposed to exist, regardless of the solubility change.
(3) The activation energy of hardening in the alloy containing 42.9% of Mn which was quenched from 750° and aged at 400∼550° was about 23,600 cal/mol., but it was very small in the alloy of 61.3% of Mn.
