纳米金属结构材料的韧化  

Toughening of Nanostructured Metals

作　　者：赵永好[1] 毛庆忠 ZHAO Yonghao;MAO Qingzhong(Nano and Heterogeneous Materials Center,School of Materials Science and Engineering,Nanjing Universityof Science and Technology,Nanjing 210094,China)

机构地区：[1]南京理工大学材料科学与工程学院纳米异构材料中心,南京210094

出　　处：《金属学报》2022年第11期1385-1398,共14页Acta Metallurgica Sinica

基　　金：国家重点研发计划项目No.2021YFA1200203;国家自然科学基金项目No.51971112;中央高校基本科研业务费专项资金项目No.30919011405。

摘　　要：金属结构材料因其独特性能(高强韧、耐高温等)在航空、航天、航海、军工、核电、化工、建筑和桥梁等领域具有广泛的工业应用。当前金属结构材料面临着挑战和发展机遇,而我国金属结构材料行业亦面临发展优势和不足。纳米金属结构材料因其高强度而在有节能减重要求的领域(如交通运输)具有工业应用前景,但其低的断裂延伸率限制了工业应用。纳米金属低的拉伸塑性是由其低的应变硬化率导致,而低的应变硬化率进一步由纳米金属过小的晶粒尺寸难以积累位错所致。经过20多年的研究,纳米金属低的断裂延伸率可通过纳米析出、孪晶界、多尺度晶粒分布、孪生、相变、降低位错密度、纳米梯度结构、异构等组织调控得以改善,这些韧化方案提高了纳米金属位错积累能力和应变硬化率,并最终提高了韧性。纳米金属结构材料的拉伸性能除了与其微观结构密切相关,还与变形温度、应变速率、拉伸样品尺寸及加载应力状态相关。Metallic structural materials have a wide range of industrial applications(including in the aviation,aerospace,navigation,military industry,nuclear power,chemical industry,construction,and bridge-building fields) due to their unique properties(such as heat resistance and high strength and toughness).At present,there are development opportunities for metallic structural materials,but these materials are also facing challenges due to the gradual substitution of carbon fiber composites and the increasing shortage of metal mineral resources.China’s metallic structural material industry is facing development roadblocks and opportunities.Nanostructured metals and alloys have a wide range of potential industrial applications in the field of aviation,aerospace,navigation,military industry with requirements for energy conservation and weight reduction due to their high strength,but their low fracture elongation is a major limitation.The low ductility of nanostructured metals is caused by their low strain hardening rate;the strain hardening rate is caused by the difficulty of dislocation accumulation.This is because the small grain size limits dislocation propagation and reaction.After more than 20 years of research,the low ductility of nanostructured metals has been improved by tailoring the metal microstructures,such as by introducing nano-precipitation,twin boundaries,multi-scale grain distribution,twinning,or phase transformation,nano-gradient structure,and heterogeneous structure,or by lowering dislocation density,etc.These toughening schemes improve the dislocation accumulation capacity and strain hardening rate of nanostructured metals,and ultimately improve their toughness.The tensile properties of nanostructured metals are closely related to their microstructures and deformation temperature,strain rate,tensile sample size,and loading state.

关 键 词：纳米金属结构材料 强度 断裂延伸率 应变硬化 韧化 

分 类 号：TG113[金属学及工艺—物理冶金]