Study on High Temperature Tensile Properties of Pure Tantalum Prepared by Selective Laser Melting
Mechanical properties of pure tantalum samples transversely or longitudinally formed by using selective laser melting(SLM)were investigated.The microstructure and phase composition of the prepared tantalum samples were studied by SEM and XRD,and their hardness and tensile properties at room tem-perature and high temperature were studied using microhardness tester and universal testing machine.The results show that the tantalum samples transversely formed by SLM exhibit a microstructure of equiaxed grains while the tantalum samples longitudinally formed by SLM show a miscrostructure of elongated grains.The phase composition of the SLM tantalum samples is BCC-Ta,with a Ta content over 99.995％.Meanwhile,the average compactness of the samples reaches 99.87％and the average microhardness is 191 HV.The SLM tantalum samples exhibit excellent strength and ductility at room temperature.How-ever,as the tensile temperature increases,their strength and ductility decrease,with the ductility reaching its worst at 600 ℃ due to dynamic strain aging.The fracture morphology at room temperature of the SLM tantalum samples is ductile fracture,and the cleavage characteristics of the fracture become more obvious as the tensile temperature increases.At 1 200 ℃,the fracture surface exhibits severe oxidation corrosion,presenting characteristics of intergranular oxidation corrosion cracking.Within the temperature range from room temperature to 1 200 ℃,the tensile properties of the tantalum samples longitudinally formed by SLM are slightly better than those of the tantalum samples transversely formed by SLM.
tantalumselective laser meltinghigh temperature tensionhardnessmechanical propertyfrac-ture morphology
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