Experimental Measurement Of Interdiffusivities And Calculation Of Diffusion Kinetics In Some Fcc Co-based Alloys Systems

The cobalt-based alloys exhibit excellent magnetic properties,wear resistance,heat resistance,corrosion resistance and biocompatibility.which leads to their wide applications in the vane and conduit of gas turbine?jet engine?rocket motor?anti-corrosion alloy and permanent magnetic alloy,etc.Because a lot heat treatment processes and phase change of cobalt-based alloys are closely connected to the diffusion behavior of alloy elements,it is essential to research the diffusion of materials with experiments and theoretical calculation.However,there are very little experimental data,diffusional kinetic database of cobalt-based alloys is not complete now.Therefore,in this work,interdiffusion coefficients of part of fcc cobalt-based binary systems and ternary systems were measured experimentally by means of diffusion couples.Based on the experimental data determined in this work as well as the thermodynamic information and atomic mobilities in the literatures,the mobility parameters were assessed by using the DICTRA software.The main content of this research are as follows:(1)The diffusion couples of the fcc Co-X(X=Ga?V?Ti)binary systems were prepared in this work,then the concentration-distance curve of each diffusion couple was determined using the EPMA technology.After that the interdiffusion coefficients of the fcc Co-Ga and Co-V binary systems were calculated in the temperature range of 1273-1573 K by Den Broeder method.Based on the experimental data determined in the present work as well as the thermodynamic information and atomic mobilities in the literatures of the two binary systems,the mobility parameters of fcc phase Co-Ga and Co-V systems were assessed by using the DICTRA software.And the concentration-distance curve of each difusion couple was calculated with the mobility parameters obtained,and a good agreement is received from comprehensive comparison between the calculated results and the experimental ones,which further verify the veracity of the mobility parameters.(2)The diffusion couples of the fcc Co-Cr-V?Co-Ni-V and Co-Cr-Cu ternary systems at the temperature of 1373 K or 1473 K were prepared in this work,then the concentration-distance curve of each diffusion couple was determined using the EPMA technology.the diffusion coefficients of these ternary systems were calculated by Whittle and Green method.And based on the experimental data in this work as well as the thermodynamic information and atomic mobility parameters of the related binary systems in the literature,the mobility parameters of the fcc Co-Cr-V and Co-Ni-V ternary systems were assessed by DICTRA.And the concentration-distance curve and difiusion path of each difusion couple were calculated.The calculation results are well consistent with the experimental data,which further verify the accuracy and validity of the mobility parameters.