3D Printing Technology Of Laser Cladding Fe Based Amorphous Alloy Coating

Amorphous alloys have excellent physical and chemical properties due to their special atomic arrangement structure.As a new surface modification technology,Laser cladding(Laser Cladding,CL)can make the original powder melt in the high-power Laser beam to the surface of the substrate,and form a coating with high density and metallurgical bonding with the substrate.In this paper,Fe55Cr25Mo16C2B2 amorphous alloy coating was prepared by laser cladding.There are many factors affecting the formation of amorphous alloy coating and they interact with each other.Firstly,based on the effect of laser power P and laser scanning speed V on the coating during the processing,more groups of parameters of laser cladding and single cladding coating experiment were done on the 304 stainless steel substrates,found in the cladding parameters for P = 1600 W,V = 40 mm/s conditions can work out a good quality surface and the coating is partially amorphous.In addition,in view of the impact of cladding matrix material on the amorphous forming capacity of coating.99.9% pure molybdenum plate is used as the cladding matrix to prepare amorphous alloy coating.When the processing parameters are P=2000W and V=50mm/s,the near-complete amorphous Fe-based amorphous alloy coating can be obtained.The mechanical properties of hardness,compressive strength and fracture toughness of Febased amorphous alloy coatings were studied in this paper.The hardness of the coating prepared under different processing conditions was measured by nano-indentation instrument,and the influence of crystallization on the hardness was analyzed by combining with the XRD curve.The hardness of the Fe-based amorphous alloy coating prepared in this paper was measured to be about 14.5GPa.In the compression strength test,samples were prepared,compressed and observed by focusing ion beam,nano-indentation instrument,scanning electron microscope and other equipment.According to the stress-strain curve,the compressive strength of the Fe-based amorphous alloy coating was about 4340 MPa.An experimental model for measuring fracture toughness was established based on the theory of continuous damage mechanism.The indentation test method with constant rate and constant peak growth of Fe-based amorphous alloy coating was used to calculate the fracture toughness of Fe-based amorphous alloy with 58.59MPam^1/2,the error range of the results calculated by this method is within 10%.The microstructure changes of Fe-based amorphous alloy coatings after heat treatment at different temperatures were studied.The experimental results show that the coating does not undergo obvious crystallization after heat treatment at 580?(in the supercooled liquid region),and still presents all the pale amorphous phases under the scanning electron microscope.When the temperature rises above the crystallization temperature,with the increase of the heat treatment temperature,nanocrystallization began to occur and the crystal size gradually increased.According to the calculation of xie le formula,under the conditions of heat treatment temperature of 580,650?,800? and 900?,the average grain size of coatings are successively less than 10 nm,20nm,40 nm and 34 nm.At the same time,the influence of the change of the microstructure of the coating on its microhardness was also studied.The experimental results showed that the hardness of the coating increased first and then decreased with the increase of the heat treatment temperature,and reached the maximum value was about1651 HV at the heat treatment temperature of 650?.