Mn-Bi-(A1) 합금계의 상분석 및 자기적 특성 연구

Abstract

본 연구에서는 Mnx-Bi(X=0.5, 1, 2, 3, 4, 5, 6, 7, 8) 및 Mn-Bi-Al 합금계의 상분석, 열처리 효과 및 자기적 특성에 대하여 X-선 회절분석기, 주사전자 현미경 및 진동시료형 자력계를 이용하여 분석하였다.

Mnx-Bi합금계에서는 전조성에서 Hexagonal 구조의 a=4.293Å, c=6.143Å인 MnBi상과 Hexagonal 구조의 a=4.546Å, c=11.898Å인 Bi상 및 격자상 수가 a=6.311Å인 Cubic 구조의 β-Mn상이 확인 되었으며 Mn함량이 증가할수록 Bi상이 상대적으로 감소하고 β-Min상은 증가하는 현상을 확인할 수 있었다. Mn-Bi-Al합금계에서는 Hexagonal 구조의 a=4.293Å, c=6.143Å인 MnBi상과 Hexagonal 구조의 a=4.546Å, a=11.898Å인 Bi상으로 이루어져 있음을 확인할 수 있었다.

상온에서의 자기적 특성은 Mn-Bi 합금계에서는 MnBi(x=1)합금이 가장 큰 자화값을 나타낸 반면, Mn-Bi-Al 합금계에서는 MnBi0.75Al0.25합금이 가장 큰 자화값을 나타내었다.

MnBi, Mn₂Bi 및 MnBi0.75 Al0.25 합금은 250±3℃, 260±3℃에서 진공상태에서 소둔하여 수냉하였을 때 열처리 하지 않은 시편과 비교시 자화값이 증가하는 현상을 보여주었으며 이는 MnBi상의 상대적인 증가에 인한 것으로 보인다.

Phase analysis and magnetic properties measurements on Mnx-Bi(X=0.5, 1, 2, 3, 4, 5, 6, 7, 8) and Mn-Bi-Al alloys have been made in this work.

Hexagonal MnBi phase with lattice parameter a=4.293Å, and c=6.143Å and Bi phase which has also hexagonal structure with a=4.545Å and c=11.898Å, were found throughout the whole composition range of MnxBi and Mn-Bi-Al alloys. As Mn contents increed in MnxBi alloys. β-Mn phase with a=6.312Å was found increasing on the cost of Bi pase.

At room temperatures. MnBi(x=1) among MnxBi alloys showed the largest magnetization while MnBi0.75 Al0.25 in Mn-Bi-Al alloys showed the strongest ferromagnetism. The magnetization of MnBi. Mn₂Bi and MnBi0.75Al0.25 increased a lot when heat treated in vacuum at 250±3℃, 260±3℃ at some specimens followed by water quenching. This seems sue to increase of fraction of MnBi phase through heat treatment.

Phase analysis and magnetic properties measurements on Mnx-Bi(X=0.5, 1, 2, 3, 4, 5, 6, 7, 8) and Mn-Bi-Al alloys have been made in this work.

Hexagonal MnBi phase with lattice parameter a=4.293Å, and c=6.143Å and Bi phase which has also hexagonal structure with a=4.545Å and c=11.898Å, were found throughout the whole composition range of MnxBi and Mn-Bi-Al alloys. As Mn contents increed in MnxBi alloys. β-Mn phase with a=6.312Å was found increasing on the cost of Bi pase.

At room temperatures. MnBi(x=1) among MnxBi alloys showed the largest magnetization while MnBi0.75 Al0.25 in Mn-Bi-Al alloys showed the strongest ferromagnetism. The magnetization of MnBi. Mn₂Bi and MnBi0.75Al0.25 increased a lot when heat treated in vacuum at 250±3℃, 260±3℃ at some specimens followed by water quenching. This seems sue to increase of fraction of MnBi phase through heat treatment.