中高熵合金的异构设计及其强韧化机理  

Architecture design and strengthening-toughening mechanisms in heterogeneous-structured medium/high entropy alloys

作　　者：邢汉峥 李晓雁[1] Hanzheng Xing;Xiaoyan Li(Department of Engineering Mechanics,Tsinghua University,Beijing 100084,China)

机构地区：[1]清华大学工程力学系,北京100084

出　　处：《科学通报》2024年第26期3864-3886,共23页Chinese Science Bulletin

基　　金：国家自然科学基金(12325203)资助。

摘　　要：不同于传统合金,中高熵合金的多主元元素设计使其展示出了独特的结构特征,并表现出中高熵效应、晶格畸变效应、迟滞扩散效应和“鸡尾酒”效应.因此,中高熵合金展示了优异的力学性能,如超高的强度、良好的延展性、突出的耐磨性、抗腐蚀性.然而,中高熵合金依然面临着与传统金属和合金材料同样的强度-延展性相互制约的挑战.通过对中高熵合金的元素成分比例和加工工艺进行设计与调控,其内部能够形成稳定的跨尺度的异质结构,包括原子尺度的局域化学有序、纳米尺度的析出相、亚微米尺度的第二相或晶内缺陷(如纳米孪晶、位错等)以及微米尺度的多模晶粒尺寸.这些通过精心设计的加工工艺引入的、或是在塑性变形过程形成的跨尺度的异质结构能够显著影响材料的塑性变形机制.跨尺度的异质结构能够在阻碍位错运动的同时提高加工硬化能力,从而提高材料强度,并改善材料的延展性.因此,异构设计有助于实现中高熵合金强度与延展性的协同提升.本文对近年来关于中高熵合金的不同尺度的异构设计工作进行了总结评述,同时揭示了不同异构中高熵合金所对应的强韧化机理,最后总结了中高熵合金中异质结构与变形机制和力学性能之间的关系,并对今后研究的重点和方向进行了展望.Metallic materials are indispensable structural materials in modern industry and play an important role in energy,environmental protection,advanced manufacturing,aerospace and aviation,owing to their high strength,high thermal conductivity,high electrical conductivity and processability.To meet the increasingly diversified engineering applications,metallic materials are demanded to exhibit excellent mechanical properties and performances,such as high strength,high toughness,corrosion resistance,creep resistance and good thermal stability.As two most important mechanical properties of metallic materials,strength and ductility are often mutually exclusive,which is attributed to a complex coupling between mechanical properties and microstructures of metallic materials.Traditional strengthening methods have been utilized to enhance strength by impeding the dislocation motion or improve the interactions among dislocations.However,traditional strengthening methods can limit dislocation multiplication and storage capacity,leading to insufficient work hardening capacity,premature plastic destabilization and consequent reduction in ductility.As a novel class of alloys,medium/high entropy alloys are a mixture of three or more metallic elements with equiatomic or near equiatomic ratio,with each element being regarded as a principal component.Different from the conventional alloys,medium/high-entropy alloys demonstrate unique structural features and exhibit the medium/high-entropy effect,lattice distortion effect,sluggish diffusion effect,and“cocktail”effect,which is attributed to the presence of the multi-principal elements.Medium-high entropy alloys possess superior mechanical properties,such as ultrahigh strength,excellent ductility,remarkable wear resistance and corrosion resistance.However,like traditional metal and alloys,medium/high entropy alloys encounter a persistent dilemma of balancing strength and ductility,i.e.a strength-ductility trade-off.Biomaterials in nature exhibit excellent mechanical properties,whic

关 键 词：中高熵合金 异质结构 塑性变形 力学性能 强韧化机理 

分 类 号：TG139[一般工业技术—材料科学与工程]