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为充分拓展DSC测量功能、探寻居里温度的简便测量方法、尤其是探寻高温居里温度的耐久测量方法,对真空电弧熔炼(Nd,Pr)12.8Dy0.2Fe77.4Co4B5.6铸锭,先通过PPMS测量升温速率3 K·min-1时样品的M-T曲线,并用外推法得到居里温度为648.3 K;然后采用DSC分别以3,10,20,30,40 K·min-1速率测量样品的升、降温曲线,分析升、降温曲线上对应吸、放热峰的起始点、峰值、终止点的特征温度值;再分别用最小二乘法拟合特征温度与升降温速率的直线方程,计算升降温速率分别为0和3 K·min-1时特征温度值,并与PPMS测量的居里温度值进行比较。结果表明:由DSC升温曲线起始点的特征温度拟合直线方程计算的升温速率为3 K·min-1的特征温度值为649.1 K,与PPMS外推法得到的居里温度相对差值最小为0.12%,具有足够的精确度。
In order to fully extend the DSC measurement function and explore the simple measurement method of Curie temperature, in particular to find a durable measurement method of Curie temperature at high temperature, the vacuum arc melting (Nd, Pr) 12.8Dy0.2Fe77.4Co4B5.6 ingot is firstly passed PPMS was used to measure the MT curve of the sample at a heating rate of 3 K · min-1, and the Curie temperature was estimated to be 648.3 K by extrapolation. Then the sample was measured at 3, 10, 20, 30 and 40 K · min- The temperature rise and fall curves were used to analyze the characteristic temperature values of the onset, peak and termination points of the corresponding aspiration and exothermic peaks on the ascending and descending temperature curves. Then, the least square method was used to fit the straight-line equation of the characteristic temperature and the ascending and descending rate respectively The temperature rising and cooling rates were 0 and 3 K · min-1, respectively, and compared with the Curie temperature measured by PPMS. The results show that the characteristic temperature at a heating rate of 3 K · min-1 is 649.1 K, which is calculated from the fitting equation of the characteristic temperature at the beginning of the DSC curve, and the minimum relative difference between the Curie temperature and the PPMS extrapolation is 0.12%, with sufficient accuracy.