摘要
利用严重塑性变形以及电沉积等方法制备的块体纳米晶、超细晶材料具有优越的力学性能以及独特的物理化学性能,但其韧性和抗应变局域化能力显著降低,加工硬化能力消失。块体纳米晶、超细晶材料由于具有较高的强度,能有效抑制疲劳裂纹萌生,从而有效提高应力控制循环载荷作用下的高周疲劳性能,但其塑性差,缩短了应变控制作用下的低周疲劳寿命。事实上,工程结构疲劳失效往往起源于材料表面,在循环载荷作用下,疲劳裂纹通常从材料表面萌生并向内部扩展。因此,优化材料表面微观组织结构和性能有利于提高其服役寿命。为此,近年来,人们通过开发一些新颖的表面改性方法来制备梯度纳米结构材料,这些方法也被称为表面自纳米化。与其他传统的表面改性技术相比,利用表面纳米化技术在金属材料表面制备梯度纳米结构表层,所得纳米结构表层具有硬度高、表面粗糙度小以及梯度层厚等特点。梯度纳米结构材料表层由纳米晶构成,而芯部仍然保持未变形粗晶基体结构,晶粒尺寸由表及里逐渐从纳米尺度变化到微米尺度,这一特殊的材料构筑形式使其具有优越的抗高、低周疲劳性能。目前,关于梯度纳米结构材料的力学性能,尤其是疲劳性能的研究已经成为该领域的一大研究热点,许多工程实际应用都得益于这一领域的研究成果,然而,目前尚缺乏文献系统总结这一研究成果。为此,本文系统总结了近年来关于梯度纳米结构材料疲劳性能研究的最新进展,对影响其疲劳性能的因素进行了深入分析,对梯度纳米结构材料疲劳性能研究所面临的许多亟待解决的基础科学问题进行了讨论和展望,为梯度纳米结构材料在这一工程领域的应用提供借鉴。
The bulk nano/ultrafine grained(NG/UFG)metals were prepared by means of severe plastic deformation(SPD)or electrodeposition,which display many attractive physicochemical and mechanical properties,but the toughness and strain localization resistance of bulk NG/UFG metals significantly decrease,and the work-hardening ability disappears.Therefore,The high cycle fatigue lifetime(HCF)of bulk NG/UFG metals under stress-controlled cyclic loading was increased by suppressing fatigue crack initiation on account of its high strength,while the low cycle fatigue lifetime(LCF)under strain-controlled cyclic loading usually decreases due to lack of ductility.In practice,the fatigue failure of engineering structures mostly originates from the surface of materials,the fatigue cracks usually initiation from material surfaces and propagate into interior during cyclic loading.Therefore,the optimization of the microstructure and properties of material surface was beneficial to improving its service life.For this purpose,these novel surface modification approachs were developed to synthesize a gradient nanostructured(GNS)materials in recent years,referred to as surface self-nanocrystallization(SNC).With these SNC techniques,a thicker nanostructured layer with higher surface hardness,a large residual compressive stress and much smaller surface roughness can be achieved on the metallic surface.The surface of GNS materials was composed of nanograins,while the core remains coarse-grained structures,from the surface to the interior,the grain sizes gradually range from nanometer scale to micrometer scales,the special construction shape of GNS materials was able to effectively enhance its fatigue resistance performance in both high-cycle and low-cycle regimes.At present,the research on the mechanical properties,especially the fatigue properties,of gradient nanostructured materials has become research hot spot in this field,many engineering applications benefit from the research results in this field,however,at present,the research results on the field are defective summarized.Therefore,in this paper,the research progresses on the fatigue properties of gradient nanostructured materials in recent years is systematic summarized,and many factors that cause fatigue fracture of gradient nanostructured materials were analyzed,and perspectives and challenges on basic scientific understanding of fatigue properties of gradient nanostructured materials are addressed,which provides reference for the engineering application of gradient nanostructured materials in this field.
作者
付磊
林莉
罗云蓉
谢文玲
王清远
李辉
FU Lei;LIN Li;LUO Yunrong;XIE Wenling;WANG Qingyuan;LI Hui(School of Aeronautics and Astronautics,Sichuan University,Chengdu 610065,China;School of Mechanical Engineering,Sichuan University of Science&Engineering,Zigong 643000,China;School of Materials Science and Engineering,Sichuan University of Science&Engineering,Zigong 643000,China)
出处
《材料导报》
EI
CAS
CSCD
北大核心
2021年第3期3114-3121,共8页
Materials Reports
基金
国家自然科学基金项目(11572057)
四川省科技支撑计划项目(2015JPT0001)
四川省粉末冶金工程技术研究中心开放基金课题项目(SC-FMYJ2019-07)
过程装备与控制工程四川省高校重点实验室项目(GK201808,GK201816)
桥梁无损检测与工程计算四川省高校重点实验室项目(2018QYJ03,2018QZY01)。
关键词
梯度纳米结构材料
块体纳米金属
疲劳性能
gradient nanostructured materials
the bulk nanocrystalline metals
fatigue properties
