Effect Of Alloying Elements On Microstructure And Mechanical Properties Of High Entropy Alloys

Three groups of high entropy alloys (1)AlFeCrNiMox(0.1≤x≤1.25);(2)AlxFeCr-NiCoMo0.25(0≤x≤1.0);(3)FeCoNiMoX0.2(X=Al,Cr,Mn,Ti,V) were prepared in anvacuum arc furnace with a suction casting water-cooled copper mold in this paper.The effect of alloying elements on microstructure and properties of the alloys wasinvestigated.1. AlFeCrNiMoxhigh entropy alloys were prepared.The alloys were composedof single BCC solid solution phase when the Mo content was below0.25.When Mocontent reached0.25, the alloys were composed of BCC solid solution phase andordered BCC2solid solution phase.There were someσphase emerged in the alloyswhen Mo content was more than0.75.The volume fraction of the second phaseincreased with the increasing of Mo content, the microstructures were changed andthe grains became corsening.The yield strength, compressive strength and hardnessincreased with the increasing of Mo content and reached2252MPa,2612MPa and1006Hv respectively.The wear resistance of the alloys increased with the increasingof Mo content.The wear mechanism of the alloys was oxidation wear. AlFeCrNiMoxalloys were all ferromagnetic, the saturation intensity and remanent magnetism weredecreased with the increasing of Mo content.2. FeCrNiCoMo0.25Alxhigh entropy alloys were prepared. The alloy composedof single FCC solid solution phase when x=0, ordered BCC solid solution phase wasprecipitated when x=0.5and its volume fraction was increased with the increasing ofAl content.The microstructure of the alloys was dendritic structure and the alloysstructures were refined with the increasing of Al content.The increasing of Al contentenhanced the hardness，the strength and the wear resistance of the alloys but retardedthe plasticity.The hardness increased from206Hv to501Hv, the yield strengthincreased from206MPa to1680MPa, the plasticity decreased from22.8%to7.2%.The wear mechanism was mainly delamination wear. 3. FeCoNiMoX0.2high entropy alloys were prepared. The FeCoNiMo alloy wascomposed of FCC solid solution and intermetallic compound Fe3Mo two phases. Theaddition of elements Al, Cr, Mn, V did not change the phases of the alloy. There wasa new kind of intermetallic compound precipitated in the alloy after the addition ofelement Ti. The microstructures of FeCoNiMo, FeCoNiMoMn0.2, FeCoNiMoTi0.2,FeCoNiMoV0.2alloys were dendritic structure, FeCoNiMoCr0.2, FeCoNiMoAl0.2alloys were fine lamellar structure. The addition of Al, Cr, Ti enhanced the hardnessof the alloy, the highest hardness value was693Hv reached by FeCoNiMoTi0.2alloy.The alloys were all ferromagnetic, Mn, Ti, V elements decreased the saturationintensity and remanence magnetization and increased the coercive force.