在无磁场的条件下,降温过程中Bi—Mn合金在340℃发生包晶相变,顺磁性Mn1.08Bi相转变为铁磁性MnBi相,同时伴随着相的形态变化,由块状转变成片状;在10T磁场中,Mn1.08Bi相发生包晶相变的温度升高至介于360—370℃之间,且MnBi相晶体发生了分裂,分裂后的小晶体沿磁场方向定向排列和聚合.从磁场诱发应变的角度分析了磁场对相变温度和MnBi相形态的影响.
Under no magnetic field applied on Bi-6%Mg alloy the peritectic transformation from paramagnetic Mn1.08Bi phase to ferromagnetic MnBi phase happens at 340 ℃ during cooling process, while the bulk-like Mn1.08Bi phase changes to plate-like MnBi phase. The above phenomena took place at 360-370℃ under 10 T magnetic field. The transformed MnBi grains broake up and divided into small crystals, and the divided crystals aligned and aggregated along the direction of the magnetic field. Based on the theory of magnetic field inducing stress, the above phase transformation and the morphology change of MnBi phase have been analyzed.