High Temperature Erosion Performance Of High Entropy Alloy Coatings By Laser Cladding

The FeCoCr_0.5NiBSi_x（x=0.0,0.1,0.2,0.3,0.4）high entropy alloy coatings were prepared on 45 steel substrate by laser cladding.The morphology,phase composition and microstructure of the high-entropy alloy coatings were investigated by optical microscope（OM）,scanning electron microscopy（SEM）coupled with electron diffraction spectrometry（EDS）;phase structure was measured by X-ray diffraction（XRD）;the hardness,wear resistance and high temperature erosion resistance of coatings were respectively measured by vickers hardness tester,wear tester and high temperature erosion wear testing machine.Effect of Si content on the microstructure,hardness,wear resistance,high temperature oxidation resistance,and high temperature erosion resistance of FeCoCr_0.5NiBSi_x high-entropy alloy coatings were discussed,The results show that:The microstructure of the FeCoCr_0.5NiBSi_x high entropy alloy coatings were composed of FCC phase and M2B phase,the microstructure of coating were composed of pro-eutectic microstructure and eutectic microstucture.With the increase of silicon content,volume fraction of FCC phase increased,while that fraction of M2B phase decreased,the shape of eutectic changed from cellular to granulate and then disappeared.The average hardness of the coating decreased first and then increased with the increasing of silicon addition;the FeCoCr_0.5NiBSi_0.3 coating possesses the minimum hardness,which was 613HV;the FeCoGr_0.5NiBSi_0.4 coating possesses the maximum hardness,which was 820HV.The wear volume increased first and then decreased with the increasing of silicon addition;The wear volume of FeCoCr_0.5NiBSi_0.3 coating is maximum,Which was 4.06×10-3 mm3,The friction volume of FeCoCr_0.5NiBSi_0.4 coating is minimum,Which was 2.33×10-3 mm3.With the addition of Si content,the oxidation resistance of FeCoCr_0.5NiBSi_x high entropy alloy coatings were better than FeCoCro.sNiBSio.o coating at 800℃ and 100h,which is due to decrease of Fe₂O₃ of loose structure and generation of Cr₃O₄ and SiO₂ oxidation film.Among this,the oxidation resistance of FeCoCr_0.5NiBSi_0.4 coating is best.With the addition of Si content,the oxidation resistance coatings have nothing different at 900℃ and 100h.Result of generation of SiO₂ oxidation film,oxidation products were bonded together,so the oxidation resistance of FeCoCr_0.5NiBSi_0.4 coating was best.The oxidation films thickness of FeCoCr_0.5NiBSi_x high entropy alloy coatings at 900℃ were 3-4 times than 800℃,the coatings is antioxidant at 800℃ except FeCoCro.sNiBSio.o coating,and not antioxidant at 900℃except FeCoCr_0.5NiBSi_0.4 coating.As increase of erosion angle,the high temperature erosion rate of FeCoCro.sNiBSix（x=0.0,0.2,0.4）high entropy alloy coatings increased.With increase of Si content,the high temperature erosion rate decreased first and then increased.That is,the erosion rate of FeCoCro.sNiBSi0.2 coating at 90 degrees is minimum,which is 14.3 mg/cm2,the erosion rate of FeCoCr_0.5NiBSi_0.4 coating is the maximum,which is 16.2 mg/cm2.The erosion rate of FeCoCr_0.5NiBSi_0.4 coating increase with the increase of temperature.The maximum erosion rate of FeCoCro.sNiBSix（x=0.0,0.2,0.4）high entropy alloy coating was less than 304 stainless steel,among all impact angle at 650℃.