Improved thermal stability and infrared emissivity of high-entropy REMgAl_(11)O_(19)and LaMAl_(11)O_(19)(RE=La,Nd,Gd,Sm,Pr,Dy;M=Mg,Fe,Co,Ni,Zn)

作     者：Haolin Zhu Ling Liu Huimin Xiang Fu-Zhi Dai Xiaohui Wang Zhuang Ma Yanbo Liu Yanchun Zhou Haolin Zhu;Ling Liu;Huimin Xiang;Fu-Zhi Dai;Xiaohui Wang;Zhuang Ma;Yanbo Liu;Yanchun Zhou

作者机构：School of Materials Science and EngineeringBeijing Institute of TechnologyBeijing 100081China Science and Technology on Advanced Functional Composite LaboratoryAerospace Research Institute of Materials&Processing TechnologyBeijing 100076China National Key Laboratory of Science and Technology on Materials under Shock and ImpactBeijing 100081China Beijing Institute of Technology Chongqing Innovation CenterChongqing 401120China Shenyang National Laboratory for Materials ScienceInstitute of Metal ResearchChinese Academy of SciencesShenyang 110016China 

出 版 物：《Journal of Materials Science & Technology》 (材料科学技术（英文版）)

年 卷 期：2022年第104卷第9期

页      面：131-144页

核心收录：

学科分类：08[工学] 080502[工学-材料学] 0805[工学-材料科学与工程（可授工学、理学学位）] 

基　　金：supported by the National Natural Science Foundation of China under Grant Nos.51772027 and 51972089 

主　　题：High-entropy ceramics LaMgAl_(11)O_(19) Thermal stability Infrared emissivity UV-Vis absorption 

摘      要：LaMgAl_(11)O_(19)(LMA),characterized by high melting point,low density and thermal conductivity as well as good infrared emissivity,is regarded as a potential candidate for the thermal protection of hypersonic ***,the unsatisfied phase stability at high temperature results in declining of the emissivity below 6μm,which limits the extensive applications of LaMgAl_(11)O_(19).In order to overcome this obstacle,three dense bulk high-entropy ceramics,(La_(0.2)Nd_(0.2)Gd_(0.2)Sm_(0.2)Pr_(0.2))MgAl_(11)O_(19)(HE LMA-1),(La_(0.2)Nd_(0.2)Gd_(0.2)Sm_(0.2)Dy_(0.2))Mg Al_(11)O_(19)(HE LMA-2)and La(Mg_(0.2)Fe_(0.2)Co_(0.2)Ni_(0.2)Zn_(0.2))Al_(11)O_(19)(HE LMA-3),were designed and successfully prepared through solid state reaction at 1700℃for 4 h in one *** analyses show that the phase compositions of HE LMA-1,HE LMA-2 and HE LMA-3 are single-phase solid solutions with the relative density of 95.61%,95.49%and 94.31%,*** treatment experiments demonstrate that the phase composition of HE LMA-1 remains a single phase after high-temperature heating,while second phase appears in other two *** stability of HE LMA-1 is attributed to small average size differenceδ(~4%)of constitute ***,the average emissivity of HE LMA-1 in the range of 3-6μm reaches 0.9,which is significantly higher than that of LMA and other two HE LMA *** emissivity of all samples remains above 0.95 from 6 to 10μ*** the far infrared region(10-14μm),although the emissivity of these specimens decreases slightly,it still exceeds *** UV-Vis absorption spectra indicate that the formation of many discrete impurity energy levels with small intervals in HE LMA-1 promotes the f electrons to transit between adjacent impurity energy levels and conduction band,which enhances the infrared emission of HE LMA-1 below 6μ*** a word,with improved phase stability and thermal emissivity in infrared range,high-entropy REMgAl_(11)O_(19),especially(La_(0.2)Nd_(0.2)