Maximizing the scattering of multiwavelength phonons in novel biphasic high-entropy ZrCoSb-based half-Heusler alloys  

作　　者：Rongchun Chen Yu Yan Guangshu Li Ruonan Min Huijun Kang Enyu Guo Zongning Chen Xiong Yang Tongmin Wang 

机构地区：[1]Key Laboratory of Solidification Control and Digital Preparation Technology(Liaoning Province),School of Materials Science and Engineering,Dalian University of Technology,Dalian,116024,China [2]Ningbo Institute of Dalian University of Technology,Ningbo,315000,China

出　　处：《Journal of Materiomics》2024年第1期45-56,共12页无机材料学学报（英文）

基　　金：supported by the National Natural Science Foundation of China(Grant Nos.52271025,51971052,51927801,51834009);the Liaoning Revitalization Talents Program(No.XLYC2007183).

摘　　要：The thermoelectric(TE)performance of p-type ZrCoSb-based half-Heusler(HH)alloys has been improved tremendously in recent years;however,it remains challenging to find suitable n-type ZrCoSb-based HH alloys due to their high lattice thermal conductivity(κ_(L)).In this work,n-type Zr_(1−x)Ta_(x)Co_(1−x)Ni_(x)Sb HH alloys were firstly designed by multisite alloying.The evolution of the Raman peak proved that alloy scattering,phonon softening,anharmonicity,entropy-driven disorder,and precipitates had a combined effect on decreasingκ_(L)by 46.7%compared to that of pristine ZrCoSb.Subsequently,Hf_(0.75)Zr_(0.25)NiSn_(0.99)Sb_(0.01)was introduced into Zr_(0.88)Ta_(0.12)Co_(0.88)Ni_(0.12)Sb to further suppressκ_(L).Remarkably,the grain size of the biphasic HH alloys was refined by at least one order of magnitude.A biphasic high-entropy HH alloy with y=0.2 exhibited the minimumκ_(L)of∼2.44 W/(m·K)at 923 K,reducing by 67.7%compared to that of ZrCoSb.Consequently,(Zr_(0.88)Ta_(0.12)Co_(0.88)Ni_(0.12)Sb)_(0.9)(Hf_(0.75)Zr_(0.25)NiSn_(0.99)Sb_(0.01))_(0.1)exhibited the highest TE figure of merit(∼0.38)at 923 K.The cooperation between the entropy and biphasic microstructure resulted in multiscale defects,refined grains,and biphasic interfaces,which maximized the scattering of the multiwavelength phonons in HH alloys.This work provides a new strategy for further reducing the grain size andκ_(L)of medium-and high-entropy HH alloys.

关 键 词：Biphasic half-Heusler alloys Thermoelectric properties Entropy engineering Multiscale defects 

分 类 号：TG139[一般工业技术—材料科学与工程]