Investigation On Resistivity Of Melts About Zn Series And Effect Of Melt Structure On The Solidification Of Bi-Sb20% Alloy

Liquid-liquid structural transition(L-LST)has become a common concern in liquid physics these years,which enriches the phenomenology in liquid physics and shed light on the structure and property of liquid materials.However,the essence of this phenomenon is still seldom known.And its effects on the solidification of alloys need to be study.In this thesis,the experiments of the temperature dependence of electrical resistivity(p-T)of liquid Zn-Sb,Zn-Bi and the effects of the L-LST on the solidification behaviors and microstructures of Bi-Sb20%alloy are engaged in.The basic contents are as follows:(1)For Zn-Sb alloys which have compounds,six compositions are selected to be studied:Sb-25%Zn(Sb-rich),Sb-40%Zn,Sb-50%Zn(corresponding ZnSb),Sb-57%Zn (corresponding Zn₄Sb₃),Sb-61%Zn(corresponding Zn₃Sb₂),Sb-80%Zn(Zn-rich).The results shows that there is no L-LST in liquid Zn-Sb alloys.(2)For Zn-Bi alloys that may have area of liquid-liquid phases,three compositions Zn_(100-x)Bi_(x)(x=20,3 7.8,70)by area of liquid-liquid and two compositions Zn_(100-x)Bi_(x)(X=84.5,90)not by this are selected to be studied.The results show that there is no L-LST in liquid Zn-Bi alloys.(3)For Bi-Sb20%alloys,based on the L-LST,the alloys are melt at two different temperatures.The results of the solidification show that the microstructure becomes finer after solidifying from the melt experienced after the L-LST.The L-LST was not suggested to occur in Sb-Zn and Zn-Bi alloys by analyzing the p-T curves of them.The investigations on the resistivity of melts about Zn series have great significances not only on the law of liquid structures,but also the applicability of liquid-liquid structural change.Besides,overheating,melt thermal treatment,melt thermal-rate treatment has become the most active areas in condensed matter physics and material processing,and some achievements have been acquired.However,the different solidification structures are often owed to the difference of the melt's structures,and the essence of the effect need to be study further,which offer scientific evidences for progress of material technics.