材料期刊网

在评述以在工作的基础上,就目前对马氏体相变的认识提出进一步处理的概念。着重对下式的物理含义加以阐述, ΔG~(γ→M)=ΔG~(γ→a)+Δ~(α→M)提出对ΔG~(α→M)估计的概念及运算途径。改进了处理方法并以较新数据计算了ΔO~(γ→a)。由热力学处理直接求得的理论M_s值与典型实验值很好符合,指出纯铁的M_s应为800K,Fe-C合金的M_3与碳浓度及奥氏体在M_s时的屈服强度均呈线性关系;相变驱动力随碳浓度的增大及M_s的下降而增加。

An approach to further investigation of the recent understanding on marten-site transformation has been developed after reviewing the relevant previous works.In particular, the physical meaning of the following formula has been clarified: ΔG~(γ→M)=ΔG~(γ→α)+ΔG~(α→M)The concept of estimating and the means of calculating ΔG~(α→M) have been dealt with,and the method for treatment has been refined. Calculation of ΔG~(γ→α) has been madewith certain newer data. The theoretical M_s value given by direct thermodyna-mical treatment agreed fairly well with that obtained by typical experiments. It isshown that the M_s of pure iron is 800K, and a linear relationship exists between M_son one hand, and the carbon concentration of the alloy or the yield strength ofaustenite at M_s on the other. The driving force of phase transformation increaseswith the increase of carbon concentration and with the decrease of M_s.