Microstructure And Properties Of Al Based Composites Manufactured By Selective Laser Melting

Aluminum matrix composite materials have the excellent characteristics of aluminum alloy and ceramic reinforced particles.Because of their light weight,high specific strength,high specific modulus,small thermal expansion coefficient,and high temperature resistance,fatigue wear resistance and other advantages are widely used.However,there are many problems in the traditional preparation process.For example,it is difficult to uniformly distribute ceramic reinforcement particles on the matrix,the interface between the reinforcement particles and the metal matrix is difficult to infiltrate,and the interface bonding condition is not ideal.Selective laser melting technology is a laser manufacturing technology based on layered manufacturing and layer-by-layer stacking.It is not limited by the geometry of the parts,and can process parts of any complex shape without the need for traditional processing fixtures and molds.The high-energy laser beam generated by the laser used in processing can process a variety of high-hardness,high-melting alloys and ceramic materials.It has a great temperature gradient and cooling rate,making the sample structure uniform and fine,and improving the mechanical properties of the sample.In this paper,selected area laser melting technology is used to prepare aluminum-based composite materials.AlSi10Mg and nano-sized WC particles are mixed by a blender to prepare WC/AlSi10Mg composite powder.SLM technology is used to form WC/AlSi10Mg composite samples.Density,microstructure,phase,tensile properties,microhardness,corrosion performance and heat treatment on its performance.The main specific research conclusions are as follows:The metallographic structure of the composite material sample grows well,the structure is dense,and the shape of the molten pool is anisotropic.Due to the different solidification conditions,the boundary of the molten pool is cell dendrites,while the interior is dendritic dendrites,which are epitaxial growth characteristics in the growth direction.The elements in the sample are evenly distributed without macro-segregation.Only ?-Al and Si phases exist in the sample,and no other phases such as Mg2Si are found.In the as-deposited specimen,?s is 347 MPa,?b is 515 MPa,and the elongation is 4.5%.After annealing,the yield strength and ultimate strength decrease,but the ductility increases.Under the annealing conditions of 300? and 2.5h,the yield strength and ultimate strength were 305MPa and 432MPa,respectively.After annealing,the composite sample changed from brittle fracture to ductile fracture.In the fatigue test,due to severe local inclusions in the sample,fatigue cracks originated in the subsurface of the sample;fatigue fractures have cleavage fracture characteristics,and the high-cycle fatigue life of the sample follows the three-parameter Weibull and Weibull distribution.Electrochemical corrosion experiments show that the corrosion resistance of the cross-section of the deposited sample is better than that of the longitudinal section.After annealing,the corrosion resistance of the sample is greatly reduced,but the anisotropic difference is weakened.