Research On The Forming Process Of Ti/Ti₃Al Metal Composites Prepared By Selective Laser Melting

Due to its high strength,low density,and inoxidizability,pure titanium has been widely used in aerospace,automotive,and energy fields.However,the disadvantages of pure titanium,such as low hardness and poor abrasion resistance,have also become the main problems hindering the development of titanium-based materials at the same time.In order to solve the above problems,people often strengthen the titanium alloy by adding variety of solid solution elements to pure titanium during the melting process.However,common titanium alloys(such as TC4,etc.)are prone to uneven distribution in the reinforcement phase,solid solution elements,and intermetallic compounds during processing,which affects the overall performance of the material.In order to solve the above problems,this paper makes full use of the advantages of laser selective melting technology(SLM)and in-situ synthesis technology to successfully prepare the Ti/Ti₃Al composite material during the forming process,and the forming process and phase composition of the Ti/Ti₃Al composite material And related mechanical properties were studied.The main conclusions are as follows:(1)Developed an SLM forming equipment electrical control system with an open operating environment.Based on scientific research and low maintenance costs,a SLM electrical control system based on ARM+FPGA was designed.Among them,the ARM part uses Linux+Qt to develop the system's human-computer interaction interface to integrate and control the entire SLM forming process;the FPGA part serves as a signal generator,and realizes the laser galvanometer on the basis of ensuring the signal real-time and synchronization.,Lasers and precise control of each motor.(2)Ti/Ti₃Al composite samples were formed by SLM-process using Ti/Al Si10Mg composite powder prepared by planetary ball milling technology.The results show that the density of the sample increases first and then decreases with the increase of the volume energy density of the sample.When the volume energy density is 83.3 J/mm³,the density of the sample reaches the highest(98.8%),and the cross section is smooth without obvious holes and cracks.Analysis of the phase composition and microstructure of the Ti/Ti₃Al composite samples shows that Al atoms and Ti atoms in the sample formed Ti₃Al intermetallic compounds during the forming process,which was precipitated between Ti crystals and formed off-white particles with a diameter of about 200 nm.These Ti₃Al particles were evenly distributed in the sample,with no element segregation occurred.(3)The effect of volume energy density on the microhardness and wear resistance of the sample was studied.The change trend of sample hardness and friction coefficient with body energy density is the same as that of compactness.On one hand,defects such as bubbles and cracks are prone to exist inside the sample,when the volume energy density is too low or too high.These defects result in lower hardness.On the other hand,the addition of Al element changed the main wear form of the sample from adhesive wear to abrasive wear.(4)The effect of Al content on the mechanical properties and corrosion resistance of Ti/Ti3Al composite samples was studied.With the increase of Al content,the hardness,abrasion resistance and compressive strength of the samples gradually increased,while the tensile strength increased first and then decreased.In addition,the plasticity of the material decreases significantly with increasing Al content.When the content of Al Si10Mg reaches 10 wt.%,the hardness and compressive strength of the samples reach 538.56 HV and 1653.9 MPa,which are 144%and 164.48%higher than those of samples without Al.However,the tensile strength of the sample was 574.2 MPa.The average friction coefficient of the sample was increased from 0.59 to 0.46,and the wear resistance of the sample was significantly improved.In addition,the corrosion resistance of the sample was improved by adding Al Si10Mg.