Phase diagram of binary components has been included in many experimental textbooks for its important industrial applicable values. On the basis of the researches, three mutual problems were further studied in details. Firstly, the cooling curve was characterized by piecewise function and the piecewise point must be the phase transition point. All of the piecewise points on the cooling curves can not be derivative, but two half-tangents exist at each of the above piecewise points. These characteristics accord with the definition of “corner point” in calculus and the phase diagram in equilibrium state. So the basic term “corner point” is suggested now for the piecewise points on the cooling curves. Secondary, the first derivative curve of the cooling curve must be discontinuous and should not be like the continuous form shown in the literature and the discontinuous point corresponds to the phase transition point. Thirdly, according to the experimental data, the high result obtained by extrapolation method reported in the literature was due to the long period of supercooling. Satisfactory results can be obtained with limited extrapolation and step - by- step method suggested.%对二元合金相图绘制的内容,研究了3个问题:①用连续的分段函数表征二元合金相图的冷却曲线;②冷却曲线的一级导数曲线是不连续的;③根据实验数据,用有限外延法和逐步逼近法进行修正可以得到满意的结果.
展开▼
