【摘要】 在Bi 6%Mn合金从高于355℃(升温过程中MnBi化合物磁性转变温度)的固液两相区凝固过程中,研究了MnBi析出相组织在无磁场和强磁场条件下的演化过程。结果表明:在无磁场条件下MnBi析出相形态在340℃(MnBi相顺磁铁磁转变温度)附近发生突变,由较规则的六方块状变为沿ab面长大的不规则片状;10T磁场条件下析出相形态突变的温度提高到355℃左右。另外,10T磁场能够控制析出相晶粒以c轴平行磁场取向、定向聚合和熔合长大,使析出相的最终形态又趋向较规则的六方块状。更多还原

【Abstract】 The structural evolution of the MnBi precipitated phase in Bi-6%Mn alloy was experimentally studied with or without a high magnetic field applied during the alloy solidified from the semi-solid zone above 355 ℃, the magnetic transition temperature of MnBi compound upon heating. In the absence of a magnetic field, it was found that the precipitated phase changed suddenly from a shape similar to its hexagonal single crystal to an irregular oblate shape formed by a rapid growth of the grains along their ab-planes at the temperature near 340 ℃, the magnetic transition temperature of MnBi compound upon cooling. In the present of a 10 T magnetic field, the temperature at which the shape changed abruptly was increased to 355 ℃ or so. Furthermore, the MnBi grains were controlled by the 10 T field to be oriented with their c-axes, directionally aggregated and grown up along the field so that the ultimate shape of the precipitated phase was tend to be regular again.更多还原