Effect of Laser Energy Density on Relative Density, Microstructure and Mechanical Properties of Cu-Al-Ni-Ti Alloy Fabricated by Selective Laser Melting

Cu Al-Ni-Ti copper-based shape memory alloy samples are fabricated by selective laser melting (SLM) with different processing parameters. The relative density of bulk samples is measured by drainage method. The microstructure and thermal analysis of the samples are carried out. The mechanical properties of the tensile samples at different temperatures and the shape memory properties of the samples are tested and the effect of laser energy density on the relative density, microstructure and mechanical properties at room temperature are studied. The results show that the relative density of bulk samples increases first and then decreases with the increase of laser energy density and the maximum relative density of bulk samples exceeds 99.5%. When the laser energy density is moderate (107 J/mm3), the melting channel is continuous and without obvious defects. If the laser energy density is too low or too high, the melting channel of the sample will be discontinuous or spheroidization. The tensile properties of tensile samples at room temperature first increase and then decrease with the increase of laser energy density. The maximum tensile strength and elongation of the samples at room temperature are 541 MPa and 7.63%, respectively. The tensile strength and elongation of the samples at 300℃ increased to 611 MPa and 10.78%, respectively. The starting temperature of martensitic transformation is about 83℃ and the ending temperature is about 40℃. The deformation recovery rate is close to 90%. © 2020 Journal of Mechanical Engineering.