中文摘要：

借助于光学显微镜研究了磁场强度对Fe-0．76％C合金冷却转变过程的先共析铁素体显微组织的影响．结果表明：随着磁场强度的增强，该合金的先共析铁素体析出量和共析点的含碳量均明显增加．原因可归结为，强磁场使Fe-C合金的共析点向高温及高含碳量区域移动，使奥氏体向铁素体转变的初始温度升高．强磁场使先共析铁素体沿磁场方向仲长，而且随着磁场强度的增加，先共析铁素体的伸长方向与磁场方向之间夹角的平均值逐渐减小．上述现象可解释为：外加磁场使先共析铁素体晶核成为磁偶极子，并使其周围奥氏体原子作为磁偶极子更易于沿磁场方向向铁素体晶核扩散．

英文摘要：

The microstructural features of proeutectoid ferrite during transformation from austenite to ferrite in Fe-0.76%C alloy under different magnetic field intensities. It was found that the amount of proeutectoid ferrite transformed and the carbon content at eutectoid point increased considerably with the increase of magnetic field intensity. The most possible reason is that the magnetic field shifts the eutectoid point to the side of high carbon content and high temperature, which increases the starting-temperature of the transformation from austenite to ferrite. The proeutectoid ferrite grains are elongated along the magnetic field direction, and the angle between the major axis of proeutectoid ferrite and magnetic field direction is decreased with the increase of magnetic field intensity, which can be explained as follows： the proeutectoid ferrite becomes the magnetic dipolar under high magnetic field, and then the polarized austenite atoms are more easy to diffusion to ferrite grain along the magnetic field direction.