STUDY ON THE MECHANICAL PROPERTIES OF
AlCrCoFeNi HIGH ENTROPY ALLOYS
Abstract:Principal elements of high—entropy alloys is only just emerging in recent years，
which is a new type of material science．Its biggest feature is the breakthrough of the traditional alloy that only one or two kinds of metal elements based design
framework,develop a new alloy design concept．High-entropy alloys based on equimolar or nearly equimolar ratio five or more than five key elements，taking melting，sintering or other means to get a combination of the metallic material．The increase of the key elements lead to produce high—entropy effect，crystal structure tend to form a simple body—centered or simple face—centered structure，intergranular compounds also may be accompanied by the generation,even in the cast it will be precipitated nanocrystals．This phenomenon is playing a solid solution strengthening，precipitation strengthening and dispersion strengthening effect，which making the performance of high一entropy alloys have greater advantages compared to conventional alloys．
This paper picks AI、Cr、Co、Fe、Ni five commonly used metals.Using vacuum arc furnace melting alloy,Alloy cast and annealed State of study on hardness and wear resistance test.
Found：The five elements generated by the smelting of high - entropy alloy its hardness is significantly higher than ordinary hard alloy(Its hardness is approximately hrc31).Without the heat treatment(800℃ annealing treatment) of high - entropy alloy coating hardness can reach hrc45.2.After heat treatment of high - entropy alloy coating hardness can reach hrc51.This characteristic of high entropy alloys and its internal organization has great links,Mainly formed in simple Bcc, FCC and Bcc+FCC.AlCrCoFeNi High entropy alloys wear resistance is far superior to ordinary alloys,On its spraying tool can extend the life of cutting tools.
AlCrCoFeNi Microstructure of high entropy alloys have simplified, do not tend to appear intermetallic precipitates, with nano - structure characteristics of amorphous
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structure,With high strength, high hardness, temper softening resistance, wear resistance, and other performance characteristics.so,high-entropy alloys are superior than the traditional alloy in mechanical properties and wear resistance，which can be greater to adapt to the needs of industrial production,its development and application prospects．
Keyword：high entropy alloys，
coating，hardness
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目录
1 绪论 ??????????????????????????????1 1.1概述 ?????????????????????????????1 1.2选题背景、研究的目的和意义 ??????????????????1 1.3本课题研究主要内容?????????????????????? 3 2 文献综述????????????????????????????4 2.1多主元高熵合金的定义 ?????????????????????4 2.1.1固溶体混合熵 ????????????????????????4 2.1.2高熵合金的界定 ???????????????????????5 2.2高熵合金的制备方法 ??????????????????????7 2.2.1电弧熔炼法 ?????????????????????????7 2.2.2高频感应炉加热熔炼 ?????????????????????8 2.2.3其他熔炼方法 ????????????????????????8 2.3高熵合金的特点及性能 ?????????????????????8 2.4多主元效应 ??????????????????????????10 2.4.1高熵效应??????????????????????????10 2.4.2晶格畸变效应????????????????????????10 2.4.3缓慢扩散效应????????????????????????11 2.4.4鸡尾酒效应?????????????????????????11 2.5高熵合金的应用领域??????????????????????12 3 多主元合金力学性能及组织分析?????????????????????15 3.1维氏硬度试验?????????????????????????15 3.1.1仪器介绍??????????????????????????15 3.1.2实验原理??????????????????????????17 3.1.3试验操作步骤????????????????????????18 3.1.4实验注意事项????????????????????????19 3.1.5实验内容??????????????????????????19 3.1.6实验分析结果????????????????????????21
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3.2金相组织试验?????????????????????????22
3.2.1试验机机构介绍???????????????????????22 3.2.2实验步骤??????????????????????????24 3.2.3注意事项??????????????????????????24 3.2.3实验内容????????????????????????25 4 结论??????????????????????????????28 5 参考文献????????????????????????????29 6 致谢??????????????????????????????31
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1 绪论
1.1概述
多主元高熵合金是近年来兴起的一种新型合金材料，它的最大特点是突破了传统合金只以一种或两种金属元素为主的设计框架，从而发展出一种全新的合金。多主元高熵合金是以五种或五种以上主要元素按等摩尔比或近等摩尔比经熔炼、烧结或其他方法组合而成具有金属特性的材料。主要元素的增多使合金产生高熵效应，晶体结构倾向于形成简单体心或简单面心结构，同时可能伴有晶间化合物生成，甚至在铸态就会析出纳米晶，从而起到固溶强化、沉淀强化和弥散强化效果，使高熵合金的性能比传统合金具有较大优势。
高熵合金在晶体结构及各种性质上和传统合金有极大的差异，主要包括一下几个方面：(1)不但能形成简单的BCC和FCC结构甚至易产生纳米相和无序的非晶相；(2)具有良好的热稳定性；(3)极高的硬度、温室强度和良好的塑性变形能力;(4)优越的耐腐蚀和耐磨性能。一般来说，传统概念的固溶体特性是具有较好的塑性变形能力，但硬度和强度较低，通常只能作为基体相。而基于多主元构成髙熵合金形成的固溶体有着较高的强度和硬度，甚至高于非晶合金的强度，同时还具有良好的热稳定性和耐磨耐蚀特性，为新型结构材料的设计提供了丰富的空间。
高熵合金的性能比传统合金具有较大的优越性，但高熵合金的元素种类不同，其力学性能，微观组织结构也会有所变化，故研究高熵合金具体元素的特性也是很有必要，本文就以AlCrCoFeNi为例，研究高熵合金力学性能
1.2选题背景、研究的目的和意义
材料、信息、能源被称为现代科学技术的三大支柱，而材料又是一切技术发展的物质基础。任何新的技术成就，莫不仰赖于各种相互匹配的新型材料，而新型材料中金属材料是其重要的一个方面，例如航空、航天工业所需的高温合金，核工业的核燃料、核反应堆材料，现代信息技术使用的硅、锗等半导体材料、新型磁性材料等。由于这些新技术的发展又推动研制新的材料品种和发展新的冶金生产工艺和装备。由此可见，金属材料的开发和研究是科学技术的一个基本领域。