1.Introduction Zirconium(Zr)and its alloys show great applications in nu-clear and chemical industry thanks to their appropriate me-chanical properties,low thermal neutron absorption cross-section and excellent corrosion resistance[1-3].Zr displays three dif-ferent crystal structures on the temperature-pressure phase dia-gram:the hexagonal close-packed structure(HCP,α-Zr),the body centered cubic structure(BCC,β-Zr)and the simple hexagonal structure(ω-Zr).Apart from the three crystal structures,a few studies have reported a unique face-centered cubic(FCC)struc-ture in Zr and its alloys[4-7]in the last four years.Due to the special significance of Zr as the cladding material,the influ-ence of FCC phase on the mechanical properties,corrosion re-sistance and irradiation performance of the cladding material in service is not clear.The crystallographic study of the FCC phase is a fundamental proposition of the above questions.This unique FCC structure was also observed in titanium and its alloys[8-13].The FCC phase in Zr and Ti exhibit similar properties,in-cluding identical orientation relationship(OR)and similar forma-tion mechanism.Two crystallographic ORs between HCP and FCC phases have been reported:①(11(2)0)HCP ||((1)10)FCC,{0001}HCP ||{111}FCC;②(0001)HCP ||(001)FCC,{10(1)0}HCP ||{110}FCC.The former and later one was called basal-type(B-type)and prismatic-type(P-type)OR,respectively.Formation mechanism for B-type FCC phase was widely believed that Shockley partial dislocations with Burgers vector of 1/3[0(1)10]glide on every other{0001}basal planes.How-ever,this mechanism has not been proved by solid experimental evidence.

Fusen Yuan;Fuzhou Han;Yingdong Zhang;Ali Muhammad;Wenbin Guo;Jie Ren;Chengze Liu;Hengfei Gu;Geping Li;Gaihuan Yuan

Shi-changxu Innovation Center For Advanced Materials,Institute of Metal Research,Chinese Academy of Sciences,72 Wenhua Road,Shenyang 110016,China;School of Materials Science and Engineering,University of Science and Technology of China,96 JinZhai Road,Baohe District,Hefei 230026,China;University of Chinese Academy of Sciences,19 Yuquan Road,Beijing 100049,China;State Nuclear Bao Ti Zirconium Industry Company,Baoji 721013,China

材料科学技术（英文版）

[1]Fusen Yuan;Fuzhou Han;Yingdong Zhang;Ali Muhammad;Wenbin Guo;Jie Ren;Chengze Liu;Hengfei Gu;Geping Li;Gaihuan Yuan-.Intermediate state of hexagonal close-packed structure to face-centered cubic structure transformation:Direct evidence for basal-type face-centered cubic phase via partial dislocation in zirconium)[J].材料科学技术（英文版）,2022(03):44-50

Zirconium,proposition

Intermediate,state,hexagonal,close,packed,face,centered,cubic,transformation,Direct,evidence,basal,type,via,partial,zirconium,Introduction,Zr,its,alloys,show,great,applications,nu,clear,chemical,industry,thanks,their,appropriate,properties,low,thermal,neutron,absorption,cross,section,excellent,corrosion,resistance,displays,three,dif,ferent,structures,temperature,pressure,gram,HCP,body,BCC,simple,Apart,from,few,studies,have,reported,unique,FCC,last,four,years,Due,special,significance,cladding,material,influ,mechanical,irradiation,performance,service,not,crystallographic,study,fundamental,above,questions,This,was,also,observed,titanium,Ti,exhibit,similar,cluding,identical,orientation,relationship,mechanism,Two,ORs,between,phases,been,former,later,one,called,prismatic,respectively,Formation,widely,believed,that,Shockley,dislocations,Burgers,vector,glide,every,other,planes,How,this,proved,by,solid,experimental

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