Grain refinement is the most universal and effective method of strengthening metallic materials, which is known as the “Hall-Petch” relationship. However, when grain size is refined to sub-micro regime (Ultrafine Grain, UFG) or even nano regime (Nano Grain, NG), the plasticity of metallic materials becomes poor. Massive studies indicate that the low strain hardening ability resulted from the enhanced dynamic recovery and lack of dislocation accumulation in fine grains is the main reason for low ductility in UFG/NG metals. To resolve this “strength-ductility” conflict, different strategies have been taken, like bimodal/multimodal structure, nanotwins, gradient structure and intragranular nano dispersoids. Among them, the introduction of nano dispersoids into the fine grains attracted lots of attention due to its wide applicability and great success in simultaneously increasing the strength and ductility of the UFG/NG metal. In addition to the enhanced mechanical performance, the introduced second-phase particle may also bring some extraordinary functional properties into the metallic material. In this paper, a brief view of the strategies to improve ductility of the UFG/NG metals and the relevant toughening mechanisms are revealed. Special attentions are paid to the utilization of intragranular nano dispersoids in Aluminum alloys.

中文翻译：

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纳米弥散体同时增强纳米和超细晶粒金属的强度和延展性：简述

细化晶粒是增强金属材料的最通用，最有效的方法，被称为“霍尔-Petch”关系。然而，当将晶粒尺寸细化至亚微米级（Ultrafine Grain，UFG）或什至纳米级（Nano Grain，NG）时，金属材料的可塑性变差。大量研究表明，细晶粒中动态恢复增强和位错积累不足导致的低应变硬化能力是UFG / NG金属延展性低的主要原因。为了解决这种“强度-延展性”冲突，已采取了不同的策略，例如双峰/多峰结构，纳米孪晶，梯度结构和颗粒内纳米弥散体。其中，由于纳米分散体的广泛适用性以及在同时提高UFG / NG金属的强度和延展性方面的巨大成功，将纳米分散体引入细晶粒引起了很多关注。除了增强的机械性能外，引入的第二相颗粒还可以为金属材料带来一些非凡的功能特性。在本文中，简要介绍了提高UFG / NG金属延展性的策略以及相关的增韧机理。要特别注意铝合金中颗粒内纳米弥散体的利用。引入的第二相颗粒还可以为金属材料带来一些非凡的功能特性。在本文中，简要介绍了提高UFG / NG金属延展性的策略以及相关的增韧机理。要特别注意铝合金中颗粒内纳米弥散体的利用。引入的第二相颗粒还可以为金属材料带来一些非凡的功能特性。在本文中，简要介绍了提高UFG / NG金属延展性的策略以及相关的增韧机理。要特别注意铝合金中颗粒内纳米弥散体的利用。