选区激光熔化成形工艺参数对CuCrZr合金组织和性能的影响

Effect of selective laser melting process parameters on microstructure and properties of CuCrZr alloys

选区激光熔化(selective laser melting,SLM)技术制备的高性能复杂结构铜铬锆合金在电子元件、传热器等领域中具有广泛的应用前景。以CuCrZr合金粉末为原材料,采用SLM技术制备了块状CuCrZr合金样品,研究了激光体能量密度对SLM CuCrZr合金微观结构和性能的影响。结果表明:随着体能量密度的增加,试样表面因输入体能量密度较低,熔池流动性差异导致的不规则孔洞减少。最佳输入体能量密度为267 J/mm^(3)(P=400 W,V=500 mm/s,h=0.1 mm),在最佳加工条件下SLM CuCrZr合金试样致密度可达98.34%,导电率为18.68%IACS,试样的极限抗拉强度和显微硬度均达到了最大值,分别为330.63 MPa和147.54HV。XRD结果表明,SLM CuCrZr合金试样的相组成仅为α-Cu,且试样的布拉格峰与CuCrZr合金粉末的布拉格峰存在明显差异,此外,根据EBSD分析,在SLM过程中试样XY面产生了{110}强织构;SLM CuCrZr合金的断裂伸长率达到40.95%,拉伸断口形貌表明,未熔颗粒和孔洞等缺陷是降低合金强度的关键因素。

Copper-chromium-zirconium alloy is a common alloy enhanced by precipitation,and it is extensively used in high-speed railway contact wires,lead frames,and heat exchange.The highperformance,complex-structured CuCrZr alloy produced by selective laser melting(LSM)has vast application potential in electronic components and heat exchangers.CuCrZr alloy powders were used as basic materials and manufactured by selective laser melting.Additionally,the effect of laser energy density on the microstructure and characteristics of SLM CuCrZr alloy was investigated.The results show that with the increase of laser energy density,the relative density of the alloy increases.At low energy density(119 J/mm^(3)),there are irregular holes on the surface of alloy sample,because the molten metal exhibits poor fluidity in the region surrounding the edge of the defect-prone molten pool.However,when the energy density increases to 267 J/mm^(3),the number of irregular holes decreases.Moreover,the relative density reaches the maximum value of 98.34%with the increasing energy density.Additionally,the electrical conductivity of the CuCrZr alloys with different process parameters is between 15.57%IACS and 18.68%IACS.Relative density is one of the variables that influence electrical conductivity,and the samples with great relative density have higher electrical conductivity than those with low relative density.Furthermore,there are significant differences in the strength and elongation properties of the samples with different process parameters.When the laser power is kept constant and the scanning speed and spacing are decreased,the strength of the alloy gradually increases.However,when the laser power increases and the scanning speed and spacing remain constant,the strength of the alloy increases accordingly.It can be concluded that the SLM process parameters have a great influence on the mechanical properties of the produced alloy.Density is intimately retated to the tensile characteristics of materials.Particularly,the greater the relative density is,the smaller the porosity of the material is,and the greater its strength is.With the increase in the bulk energy density,the degree of densification of the samples increases,and their tensile characteristics are enhanced.The SLM-5#sample,manufactured with the parameters P=400 W,V=500 mm/s,and h=0.1 mm,shows the largest relative density and the highest ultimate tensile strength(330.63 MPa),also has excellent plasticity,with the elongation of 30.81%.In addition,the sample exhibits ductile fracture properties,and the fracture surface has varying degrees of porosity and inclusion flaws.These are formed by the solidification of splash and unmelted particles generated during the SLM process,the pore size is between 3μm and 100μm,and tensile deformation traces in the form of wrinkles are dispersed around the inner walls of the holes,indicating that the samples generate significant amounts of plastic deformation during the tensile process.The presence of varying degrees of porosity and inclusion flaws on the fracture surface may disrupt the consistency of the internal structure of the molded components.The XRD spectrum indicates that the phase composition of the SLM CuCrZr alloy sample isα-Cu,and the Bragg peak of the sample significantly differs from that of the CuCrZr alloy powder.During the SLM process,the XY plane of the sample produces a strong{110}texture.The elongation at break of SLM CuCrZr alloy reaches 40.95%,and the tensile fracture morphology shows that defects such as unfused particles and holes are the key factors reducing the strength of the alloy.