析出硬化微观机制及连续化模型

Microscopic mechanisms and continuous models of precipitation hardening

析出硬化作为提升合金强度的主要方法,在低碳钢、镍基合金等工程合金中得到广泛应用.理解析出硬化效应并发展相应的理论模型对合金的强韧化设计至关重要.尽管研究者很早就开始关注析出硬化效应,并基于线张力理论发展了一系列经典的析出硬化模型,但目前仍存在由于对析出硬化微观机理等认识不够深入导致硬化模型误用的情况.鲜有综述论文系统阐述这些强化机制在微观物理过程上存在着怎样的关联关系,以及如何正确选择不同的析出硬化模型.为此,本文从位错-析出相相互作用的微观物理过程出发,通过分析长程作用和短程作用,深入探讨了基于线张力的连续化硬化模型的适用范围.同时详细介绍了不同的强化概念与位错剪切机制和Orowan绕过机制的关联关系,并分析了不同情况下位错-析出相间作用的主导机制如何随共格析出相的尺寸变化而转变.本文的工作对于深入理解析出硬化机理,有效描述析出硬化效应,指导合金设计等具有重要的参考价值.

Precipitation hardening,a primary method for enhancing alloy strength,finds widespread applications in engineering alloys such as low-carbon steel and nickel-based alloys.Understanding precipitation hardening and developing corresponding theoretical models are crucial for the design of toughened alloys.Although early researchers devoted attention to precipitation hardening and developed classical precipitation hardening models based on the line tension theory,the misapplication of these models endures due to an insufficient grasp of the microscopic mechanisms underlying precipitation hardening.There are limited reviews that comprehensively unravel the interconnection between these hardening mechanisms within microphysical processes and offer guidance for the judicious selection of distinct precipitation hardening models.To bridge this gap,this study explores dislocation-precipitate interactions and analyzes the applicability of continuous precipitation hardening models,considering long-and short-range interactions.Additionally,the links between various strengthening concepts and dislocation shear or Orowan bypass mechanisms are investigated.Furthermore,we illuminate the transition of dominant interaction mechanisms with coherent precipitate sizes,from dislocation shear to Orowan bypass.This study significantly advances the understanding of precipitation hardening mechanisms,provides a precise description of their effects,and informs the design of alloys.