珠光体-奥氏体相变是固态相变领域的重要方向，也是先进高强钢热处理工艺中的关键步骤，学习和掌握珠光体-奥氏体相变动力学规律，可以指导工业界制定合理的热处理工艺。在奥氏体相变中，合金元素配分与不配分临界转变温度PNTT是通过等温相图计算得到的相变特征温度，可以对不同温度下奥氏体相变的动力学进行预测。然而，目前常用的PNTT计算方法只能预测奥氏体在α/θ相界面形核时的相变过程，无法适用于奥氏体在珠光体团边界形核的情况，且C和合金元素在奥氏体相变中的配分与扩散规律也有待阐明。而合金元素对奥氏体相变动力学的影响，可以归纳为是否发生扩散（合金元素是否参与扩散）、如何进行扩散（C和合金元素在不同区域的扩散通量）和非温度场驱动的扩散行为对相变动力学的影响三个方面。本文研究了Fe-0.6C-2Mn合金中片层珠光体-奥氏体相变的动力学，通过实验和计算模拟阐明了合金元素配分与扩散对相变动力学的影响，为材料组织设计和热处理工艺优化提供理论指导。针对奥氏体相变中合金元素是否参与扩散的问题，对片层珠光体-奥氏体相变PNTT计算模型展开研究，通过对等温截面相图的深入理解与分析，讨论了初始珠光体组织形貌对PNTT计算的影响，提出了更适用于片层珠光体-奥氏体相变的二维PNTT计算模型；阐明了C、Mn在相界面前沿的分布情况和扩散行为，并利用实验和模拟手段对二维PNTT计算模型的合理性进行验证。针对C和合金元素的扩散通量问题，研究了C、Mn在奥氏体、铁素体和相界面中的扩散对相变动力学的贡献，通过基于MICRESS的相场方法在奥氏体相变中引入不同扩散区域，研究了珠光体片层间距和相界面前沿的扩散通量对相变动力学的影响，阐明了NPLE和PLE相变模式下C、Mn在铁素体和界面中的扩散对相界面迁移速率的贡献，并通过实验粗略估测了相界面迁移速率。针对非温度场驱动的C扩散行为对相变动力学影响的问题，对脱碳条件下表面珠光体-奥氏体相变展开研究，通过表面珠光体在705℃等温时的脱碳实验，发现了脱碳可以加速PLE模式下奥氏体沿渗碳体片层的长大速率，这是由于体系中的碳原子因脱碳发生定向长程扩散，这一结果可以加深人们对PNTT物理本质的理解。除此之外，本文也提出了基于表面珠光体的新型梯度材料的设计思路。

The pearlite-to-austenite transformation is an important issue in the solid-solid phase transformation and it is also a key step involved in the heat treatment of the advanced high strength steel (AHSS). The accurate and detailed knowledge about the kinetic laws of the pearlite-to-austenite transformation can play a guiding role in formulating reasonable heat-treatment processes in the industrial production. The critical temperature for partitioning of substitutional alloying element, namely PNTT, is the characteristic temperature of austenization, which is calculated by isothermal section of phase diagram. It can predict the dynamic characteristics of the pearlite-to-austenite transformation. However, the current PNTT model can only predict the process of austenite when nucleated at the α/θ phase boundary, which is not appropriate to the condition where the austenite nucleates the boundaries of the pearlite colonies. Moreover, the partitional and diffusional laws of the carbon and alloying elements in lamellar pearlite-austenite transformation also need to be clarified. The influence of the alloying elements on the kinetics of austenite transformation can be summarized as whether the diffusion occurs (the types of alloying elements involved in diffusion), how to diffuse (diffusional fluxes of carbon and alloying elements in various regions) and the effects of the diffusion driven by non-temperature field on the kinetics. In this research, the kinetics of the lamellar pearlite-to-austenite transformation in Fe-0.6C-2Mn alloy was studied, and the effects of the partition and diffusion of the alloying elements on the transformation kinetics were clarified through the experimental methods and simulation, which provide the theoretical guidance for the microstructural design of steel and optimization of heat treatments. The calculated model about the PNTT of the lamellar pearlite-to-austenite transformation has been studied to solve the question of the whether the alloying elements are involved in the diffusion during the phase transformation. A two-dimensional PNTT calculated model, which is more appropriate to the lamellar pearlite-to-austenite transformation has been proposed through the in-depth understanding and analysis of the isothermal sections of the Fe-C-Mn ternary phase diagram. The influence of the initial microstructure has been considered in the new PNTT model and the distribution around the phase boundary as well as the diffusional behivors of the C and Mn have been clarified. Besides, the seasonality of the model has been verified by experiments and simulation.Aiming at the problems of diffusional fluxes of carbon and alloying elements, the contributions of different types of the diffusion in austenite, ferrite and phase boundaty to phase-transformation kinetics have been studied. The different diffusional regions of alloying atoms have been introduced by the phase filed methods based on MICRESS, which is to study the effects of the spacing layer of the initial pearlite and diffusional fluxes along with the phase boundary on the kinetics of the phase transformation. The contributions of the diffusions in ferrite and phase boundary to the pearlite/austenite-boundary migration have been clarified in PLE and NPLE modes. Moreover, the migration rate of the pearlite/austenite-boundary has been roughly estimated by experiments.To solve the problem of the effects of the C-diffusion not driven by temperature field on the austenitizing kinetics, the surface pearlite-to-austenite transformation under the decarburization has been studied by the decarburized experiments of surface pearlite at 705℃. The results dictated the decarburization could make the directional long-range of carbon atoms in the materials, which would accelerate the growth rate of the austenite along the cementite lamellae under PLE transitional mode. This research can deepen the understanding of the nature of the PNTT. In addition, the idea of the new-type gradient materials based on the surface pearlite has also been proposed.