磁相变材料热膨胀与磁致伸缩效应测试

Testing of thermal expansion and magnetostrictive effect of magnetic phase transition materials

基于综合物理性能测试系统的低温与磁场环境,采用应变片测试方法开发了磁相变材料热膨胀系数的表征方法,验证了测试结果的可靠性,并开展了磁相变材料LaFe11Co0.8Si1.2负膨胀性能的研究。结果表明:在居里温度处,LaFe11Co0.8Si1.2材料的热膨胀量随温度的升高而减小,这是因为材料发生了铁磁性向顺磁性的磁相变,导致其产生磁致伸缩效应,抵消了原子非简谐振动引起的热胀冷缩,最终导致材料发生负热膨胀现象。

A characterization method for the thermal expansion coefficient of magnetic phase transition materials was developed using strain gauge testing methods based on a comprehensive physical performance testing system in low-temperature and magnetic field environments.The reliability of the test results was verified,and the negative expansion performance of magnetic phase transition materials LaFe11Co0.8Si1.2 was studied.The results show that at the Curie temperature,the thermal expansion of LaFe11Co0.8Si1.2 material decreased with the increased of temperature.The reason was that the material undergone a magnetic phase transition from ferromagnetism to paramagnetism,resulting in magnetostriction effect and offsetting the thermal expansion and contraction caused by atomic non harmonic vibration,ultimately led to negative thermal expansion of the material.