High entropy alloys (HEAs) as solid solution alloys that consist at least 4 basic elements with equal atomic ratio usually formed with between 5-35 atomic percentages of basic elements .often microstructure and properties of HEAs depend on kind and amount of constituent elements. So that if elements and compositions select truly can be received to ratio of FCC and BCC solid solution that to bring best physical and mechanical properties. in this investigation high entropy alloy of Fe Co Cr Ni prepared by mechanical alloying at different times of ball milling (10,20,30,40,50 hour ) . results of XRD tests in this stage show that FCC and BCC phase performed after 30h ball milling to investigation of the effect of change in percentage of basic atoms on this high entropy alloy , Fe x CoCrNi (x=1.3,1.6) synthesized that increasing in BCC phase fraction. Effect of addition of different atomic percentage of Zr to FeCoCrNi alloy system, microstructure and phase changes investigate by scanning electron microscope equipped with EDS , transition elector microscope and xray different ion test .thermodynamic stability of formed phase were evaluated using extended mediema model for all synthesized alloys. Thermal analysis were carried out with differential scanning calorimetric(DSC) at heating rate of 5°C/min and thermal gravimetric analysis (TGA) for all produced alloy powders. Results showed that all alloy systems have good thermal stability up to 800°C. to study of mechanical and tribological properties of alloy systems , powders compact by spark plasma sintering() method at 900°C, under pressure of 450Mpa and for 6 min. mechanical properties of compact samples studied by micro and macro hardness and shear punch tests. eventually tribological behavior of all ed samples carried out by pin on disk test for 1000m distances. Results show that increasing of Fe atomic percentage in FeCoCrNi alloy system addition to improving the mechanical properties (increasing of hardness and shear stress) improved the wear properties of these alloys. Addition of Zr and synthesis of FeCoCrNiZr 0.4 quintuple alloy improved the mechanical properties of ed samples of this alloy (UTS increase to 565Mpa and microhardness increase to 828 Vickers). Therefor in this alloy by increasing of BCC phase resistance against of plastic deformation increased and wear behavior improved.
