Origin of double-peak precipitation hardening in metallic alloys
Origin of double-peak precipitation hardening in metallic alloys
复制标题
金属合金中双峰沉淀硬化的起源
DOI：
10.1016/j.ijplas.2018.07.016
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发表时间：
2018-12
影响因子：
9.8
通讯作者：
Jaafar A El-Awady
中科院分区：
文献类型：
--
作者：
Haidong Fan;A H W Ngan;Kefu Gan;Jaafar A El-Awady
而传统的沉淀硬化是众所周知的特点是一个单一的硬度峰值，最近，双峰沉淀硬化观察到，其中第一个峰值硬度高于第二个传统的，从而提供了一种新的方法来加强材料。然而，经典的沉淀强化模型未能预测这种高强度的早期时效阶段。本文首先通过分子动力学模拟获得了纳米尺度下位错-沉淀物相互作用的真实规律，并将其引入到离散位错动力学（DDD）方法中，研究了微观尺度下的沉淀硬化效应。DDD模拟正确预测的双峰硬化，即，临界解析剪切应力（CRSS）的位错通过沉淀场首先减少，然后增加，最后减少，作为沉淀半径r p的增加。在此基础上，建立了一个与DDD模拟和实验结果吻合较好的沉淀剪切模型。基于DDD模拟和理论分析，发现三种CRSS区域分别由相干强化（CRSS <$r p− 1/2）、化学强化（CRSS <$r p− 1）和Orowan机制（CRSS <$r p− 1）控制。最后，揭示了第二个常规峰的CRSS与沉淀物尺寸之间的反比关系的普遍规律，而第一个峰被发现有利于在早期时效阶段的快速沉淀。这项工作提供了新的见解，一般沉淀硬化，特别是双峰硬化，这是非常重要的合金设计。
Whereas conventional precipitation hardening is well-known to feature a single hardness peak, recently, double-peak precipitation hardening was observed, where the first peak hardness is higher than the second conventional one, thus offering a new approach to strengthen materials. Yet, classical precipitation strengthening models fail to predict such high strengthening in the early aging stage. In this work, molecular dynamics simulations were firstly performed to obtain a realistic dislocation-precipitate interaction law at the nano-scale, which was introduced into the discrete dislocation dynamics (DDD) method so as to investigate the precipitation hardening effects at the micro-scale. The DDD simulations correctly predict the double-peak hardening, namely, the critical resolved shear stress (CRSS) for a dislocation passing through a precipitate field first decreases, then increases, and finally decreases, as the precipitate radius r p increases. Then, a precipitate shearing model was developed, which agrees well with the DDD simulations and experimental observations. Based on the DDD simulations and theoretical analysis, the three CRSS regimes were found to be controlled by coherency strengthening (CRSS∝ r p− 1/2), chemical strengthening (CRSS∝− r p− 1) and Orowan mechanism (CRSS∝ r p− 1), respectively. Finally, a universal law for the inverse relation between the CRSS and precipitate size at the second, conventional peak was unveiled, while the first peak was found to occur favorably for rapid precipitation in the early aging stage. This work provides new insights into precipitation hardening in general and double-peak hardening in particular, which are of great importance for alloy design.
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影响因子：
1.2
作者：
K. Matsuura;M. Kitamura;Katsuya Watanabe
通讯作者：
K. Matsuura;M. Kitamura;Katsuya Watanabe
影响因子：
9.4
作者：
Xiang Liu;J. B. Adams
通讯作者：
Xiang Liu;J. B. Adams
影响因子：
9.4
作者：
Xu, W.;Rivera-Diaz-del-Castillo, P. E. J.;van der Zwaag, S.
通讯作者：
van der Zwaag, S.
DOI：
10.1016/b978-0-08-096668-7.00011-5
发表时间：
2013
期刊：
--
影响因子：
--
作者：
M. Ashby
通讯作者：
M. Ashby
DOI：
10.1016/j.msea.2010.02.032
发表时间：
2010-06
影响因子：
6.4
作者：
I. Holzer;E. Kozeschnik
通讯作者：
I. Holzer;E. Kozeschnik