Miscibility Gap between Antiferromagnetic and Paramagnetic Phases in the NiMn-NiZn Pseudo-Binary System

2014 Fiscal Year Final Research Report

• Project/Area Number: 25630261
• Research Category: Grant-in-Aid for Challenging Exploratory Research
• Allocation Type: Multi-year Fund
• Research Field: Physical properties of metals/Metal-base materials
• Research Institution: Tohoku University
• Principal Investigator: OHNUMA Ikuo 東北大学, 工学(系)研究科(研究院), 准教授 (20250714)
• Project Period (FY): 2013-04-01 – 2015-03-31
• Keywords: 反強磁性合金 / 状態図 / ネール点 / 相分離 / 規則不規則変態

Outline of Final Research Achievements

It is well-known that the miscibility gap between ferro- and para-magnetic phases, so-called “Nishizawa horn”, appears along the Curie temperature (TC) curve. It is expected that such a miscibility gap also appears between antiferro- and para-magnetic phases across the Neel temperature (TN) curve due to the excess Gibbs energy of antiferromagnetism. In this study, the miscibility gap between antiferromagnetic and paramagnetic phases in the NiMn-NiZn pseudo-binary system was investigated.
Neel temperatures in the NiMn-NiZn pseudo-binary system was determined by DSC and VSM, which decreases with increasing Zn content. In the microstructure of the NiMn/NiZn diffusion couple heat-treated at 700°C for 3 months, a clear interface was recognized. Two-phase microstructures were also obtained in Ni50(Mn47Zn3) alloy heat-treated at 680°C for 1 and 3 months. In conclusion, the existence of the miscibility gap between antiferro- and para-magnetic phases along the TN curve was confirmed.

Free Research Field

材料組織学