Investigation Of Diffusion Behavior And Mechanical Properties Of Zr-Al And Zr-Fe Systems

Zirconium alloys have always been used as an important instructional material,and which have received widespread attention due to their excellent nuclear material properties,corrosion resistance,and mechanical properties in the area of nuclear structural materials.The stability of zirconium alloys mainly depends on their internal diffusion changes and the stability of the microstructure.This is vital for the safety of nuclear reactor operation.Therefore,it is great significance to deeply study the microstructure and mechanical properties of zirconium alloys.This work mainly uses the electron probe microanalyzer(EPMA)and nanoindentation tester to study the Zr-Al and Zr-Fe binary diffusion layers and determine the diffusion coefficient and mechanical properties of these binary systems.This paper mainly draws the following conclusions:(1)For the Zr-Al binary diffusion system,it is determined that the diffusion growth mechanism of the growth layer is mainly a diffusion control mechanism,and only the composition of one phase can be determined by EPMA.The pre-exponential factor and activation energy of ZrA13 phase are 2.2×109 m2/s and 356 kJ/mol,respectively.The interdiffusion coefficient of ZrAl3 phase is(1.58±0.73)×10-15 m2/s,(6.76±0.97)×10-15 m2/s,(9.33±1.00)×10-15 m2/s,(15.87±1.46)×10-15m2/s in the temperature of 550 ?,575 ?,600 ?,625?.And the coefficient increases with the temperature.(2)For the Zr-Al binary system,the intermetallic compound of ZrAl3 has the value of nanohardness and Young's modulus is determined to 9.88±0.59 GPa and 121.39±10.87 GPa.(3)For the Zr-Fe binary diffusion system,the occurrence of three phases of ZrFe2,Zr2Fe and Zr6Fe23,but the composition of the precipitated phase in the phase layer cannot be determined.The experimental results indicated that the integrated interdiffusion coefficient of each phase is increasing with the increase of annealing temperature or zirconium atomic percentage.But the diffusion reaction of each phase is very slow,and the integrated interdiffusion coefficient is also very small.The activation energies of ZrFe2,Zr2Fe and Zr6Fe23 were 289.36 kJ/mol,529.21 kJ/mol and 389.14 kJ/mol,respectively.(4)The value of nanohardness and Young's modulus of ZrFe2 were 21.54±1.25 GPa and 273.14±14.75 GPa,respectively.The value of nanohardness and Young's modulus of Zr2Fe are 11.87±0.98 GPa and 143.25±11.92 GPa for Zr-Fe binary intermetallic compound.