Phase Equilibria of the Mn-Si-Zn System at 600 A°C

The phase equilibria at 600 A degrees C of the Mn-Si-Zn system were investigated by using nineteen equilibrated alloys and two diffusion couples. The alloys were prepared by melting the pure elements in the alumina crucibles encapsulated in quartz tubes. The samples were examined by means of optical microscopy, X-ray diffraction, scanning electron microscopy (SEM), and electron probe microanalysis (EPMA). The experimental results showed no existence of ternary compounds in the Mn-Si-Zn system. The binary compound Mn(5)Si(2), the existence of which is controversial in the literature, were not observed at 600 A degrees C. A massive phase transformation for (gamma Mn) was observed due to its slow quenching. In addition, the controversial epsilon-phase region was studied. The existence of epsilon (1) was confirmed through a diffusion couple method. Though the existence of epsilon (2) (another controversial subdivision of the epsilon phase) was not confirmed, it is assumed to exist, taking into account the difference in the observed mechanical properties of the Mn-Zn binary alloys. The solubility of Zn in R-Mn(6)Si, nu-Mn(9)Si(2), Mn(3)Si, Mn(5)Si(3), MnSi, and Mn(11)Si(19) was measured to be 1.3, 0.8, 0.5, 0.8, 0.5, and 0.2 at. pct Zn, respectively. The solubility of Si in (beta Mn), (gamma Mn), epsilon, and liquid was determined to be negligible.