Nucleation and Growth of Solid-State Transformations

该研究计划旨在提高对 一阶相变的基础上审查的 马氏体相变 该方案采用了两种 针对两大领域的理论和实验方法： (a)非均相分布活化动力学 成核;和（B）竞争转化机制， 非线性非局部固体 分布式的一般特征- 活化非均相动力学在成核过程中进行了研究 采用声发射和立体学的动力学实验 热弹性和非热弹性马氏体的测量 系统，定义初始和 自催化缺陷 原理推广到贝氏体 转变和固化。 竞争机制 用组合理论检验结构转换， 用非线性非局部描述的模型系统的实验 连续介质模型预测界面能。 实验测试 一种新的转化机制的预测行为， 与形核竞争的准马氏体应变调制 以及在接近晶格不稳定性的条件下生长。 %%% 这一分析和实验工作是针对马氏体 例如，在钢中发现的转变，但适用于 金属和陶瓷中的其他相变。

This research program is directed towards improved understanding of first-order phase transformations based on examination of the martensitic phase transformation. The program employs both theoretical and experimental approaches to address two broad areas: (a) the distributed-activation kinetics of heterogeneous nucleation; and (b) competing transformation mechanisms in nonlinear nonlocal solids. General features of distributed- activation heterogeneous kinetics are examined in nucleation kinetic experiments employing acoustic emission and sterological measurements in both thermoelastic and nonthermoelastic martensitic systems, defining potency distributions of initial and autocatalytic defects. principles are extended to bainitic transformations and solidification. Competing mechanisms of structural transformation are examined by combined theory and experiment in model systems describable by nonlinear nonlocal continuum models predicting interfacial energies. Experiments test predicted behavior of a new transformation mechanism, quasimartensitic strain modulation, which competes with nucleation and growth under conditions near a lattice instability. %%% This analytical and experimental work is directed to martensitic transformations found in steels, for instance, but is applicable to other phase transformations in metals and ceramics.