晶粒取向Mn₂Sb合金的制备与负热膨胀性能研究

Preparation and Study on Negative Thermal Expansion of Mn₂Sb Alloy with Grain Orientation

摘要: 负热膨胀材料凭借着能够补偿和控制材料热膨胀性能的优点，在高精度仪器和器件的制造中发挥着至关重要的作用。具有一级磁弹性相变的Mn₂Sb基合金，在从高温铁磁到低温反铁磁的相变过程，会伴随着晶格参数的突变，表现出大的负热膨胀效应，具有巨大的应用潜力。本研究通过定向凝固技术，在具有四方晶体结构的Mn_1.9Cr_0.1Sb合金中制备出了{110}取向的样品，借助扫描电子显微镜、X射线衍射仪、综合物性测量系统以及热机械分析仪等系统地表征了其显微结构、磁性能以及负热膨胀等性能。此外，本研究通过定向凝固制备的取向Mn_1.9Cr_0.1Sb样品不但致密度高，而且还获得了线膨胀系数为α = −53.8 ppm/K的大的负热膨胀效应。同时，本研究也为其他负热膨胀材料的制备提供了新策略。

Abstract: With the advantages of compensating and controlling the thermal expansion of materials, negative thermal expansion materials play an important role in the manufacture of high-precision instruments and devices. Mn₂Sb-based alloy shows a first-order magnetic transition from high-temperature ferromagnetic state to low-temperature antiferromagnetic state. The magnetic transition is accompanied by a sudden change in the lattice parameters, leading to a large negative thermal expansion effect. In this study, {110}-oriented Mn_1.9Cr_0.1Sb alloys were prepared by a directional solidification technique. Its microstructure, grain orientation, magnetic properties, negative thermal expansion and other properties were systematically characterized by means of scanning electron microscope, X-ray diffractometer, comprehensive physical property measure-ment system and thermal mechanical analyzer. The textured Mn_1.9Cr_0.1Sb samples show not only a high density, but also a linear expansion coefficient of α = −53.8 ppm/K. Additionally, our study also provides a new strategy for the preparation of other negative thermal expansion materials.