设计制备具有优异形成能力和磁热效应的GdHoErCoNiAl高熵非晶合金  

Design and fabrication of GdHoErCoNiAl metallic glasses with excellent glass forming capability and magnetocaloric effects

作　　者：王壮 金凡 李伟[1] 阮嘉艺 王龙飞 吴雪莲 张义坤 袁晨晨 Wang Zhuang;Jin Fan;Li Wei;Ruan Jia-Yi;Wang Long-Fei;Wu Xue-Lian;Zhang Yi-Kun;Yuan Chen-Chen(School of Materials Science and Engineering,Southeast University,Nanjing 211189,China;School of Materials and Environmental Engineering,Hangzhou Dianzi University,Hangzhou 310018,China;School of Materials Science and Engineering,Anhui University of Technology,Ma'anshan 243032,China)

机构地区：[1]东南大学材料科学与工程学院,南京211189 [2]杭州电子科技大学材料与环境工程学院,杭州310018 [3]安徽工业大学材料科学与工程学院,马鞍山243032

出　　处：《物理学报》2024年第21期232-245,共14页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:52071078);东南大学至善学者A类项目(批准号:2242021R41158)资助的课题。

摘　　要：通过对Gd,Ho和Er进行元素替换,成功设计制备出临界尺寸为2 mm的Gd_(20+2x)Ho_(20-x)Er_(20-x)Co_(20)Ni_(10)Al_(10)(x=0,5,10)块体高熵非晶合金体系,系统研究了稀土元素种类和含量对高熵非晶合金的微观结构、热力学性能和磁热性能的影响及调控机理.研究结果表明,随着Ho和Er逐步被Gd取代,体系的热稳定性略有下降,其中,玻璃转变温度T_(g)和初始晶化温度T_(x)逐渐降低.与此同时,液相线温度T_(1)升高,导致玻璃形成能力的热力学判据,如约化玻璃转变温度T_(rg),γ和γ_(m)降低.X射线和高分辨透射电子显微镜的结果分析表明,随着Gd含量的增大,体系的有序度减小,有利于非晶相的生成.另一方面,随着Gd元素的加入,磁热性能参量如居里温度T_(c)、峰值磁熵变(|△S_(M)_(pk)|)和相对制冷能力(relative cooling power,RCP)均逐渐升高,其中Gd_(40)Ho_(10)Er_(10)CoNiAl的|△S_(M)_(pk)|和RCP最大,分别为8.31 J/(kg·K)和740.82 J/kg.研究结果表明,稀土基高熵非晶合金体系的磁热效应包括RCP,T_(c)和|△S_(M)_(pk)|主要依赖于de Gennes因子,与材料内部的有效磁矩并无直接关系,而热力学性能主要受到4f电子引起的f-d杂化效应影响,随着4f电子数的增加非晶合金体系的热稳定逐步增加.综上所述,我们可以借助稀土元素替换进行成分优选,通过调控4f电子数获得具有较高热稳定性且Tc可调的稀土基非晶合金磁热材料.In this work,Gd_(20+2x)Ho_(20-x)Er_(20-x)Co_(20)Ni_(10)Al_(10)(x=0,5,10)high-entropy metallic glasses(MGs)with a critical diameter of 2 mm are successfully designed and fabricated by substituting Gd,Ho and Er.The effects of type and content of rare-earth(RE)elements on the microstructure,thermodynamic behaviors,and magnetocaloric effect(MCE)are investigated systematically.The amorphous structures of the ribbons and ascast rods are confirmed by X-ray diffraction(XRD)with Cu Kαradiation(2θ=20°–80°).The atomic-scale ordered configurations are examined by using high-resolution transmission electron microscope(HRTEM).Thermal analysis is carried out on differential scanning calorimeter(DSC)with a heating rate of 20 K/min by using ribbons.The magnetic measurements are conducted by using magnetometer in a temperature range of 5–180 K.According to DSC traces,it is suggested that as Ho and Er are replaced by Gd,the thermal stability of MGs slightly decreases,for example,both glass transition temperature(T_(g))and initial crystallization temperature(T_(x))decrease gradually,meanwhile the liquidus temperature(T_(l))increases,which results in a reduction of glass-forming ability criteria such as the reduced glass transition temperatures T_(rg)(T_(rg)=T_(g)/T_(l)),γ(γ=T_(x)/(T_(g)+T_(l))),andγ_(m)(γ_(m)=(2T_(x)–T_(g))/T_(l)),thermodynamically.The analyses based on XRD and HRTEM show that the degree of order in MGs decreases with Gd content increasing,which facilitates the glass formation.The magnetocaloric parameters such as Curie temperature(T_(c)),maximum magnetic entropy change|△S_(M)_(pk)|and relative cooling power(RCP)all increase gradually with the addition of Gd.The Gd_(40)Ho_(10)Er_(10)CoNiAl exhibits the best refrigeration performance in all studied systems,where the peak value of|△S_(M)|is 8.31 J/(kg·K)and RCP is 740.82 J/kg.The results indicate that MCEs of MGs including RCP,T_(c)and|△S_(M)_(pk)|,mainly depend on the de Gennes factor rather than the effective magnetic moment,while thermodynamic

关 键 词：稀土基高熵非晶合金 热力学性能 磁热效应 非晶形成能力 

分 类 号：TG139.8[一般工业技术—材料科学与工程]