纳米压/划痕表征激光渗氮层的弹塑性力学性能

Elastic-plastic mechanical properties of laser nitriding layer on Ti6Al4V alloy characterized by nanoindentation and nanoscratch

利用脉冲式Nd:YAG激光在Ti6Al4V合金表面进行激光渗氮处理,借助纳米压痕和划痕试验表征渗氮层的弹塑性力学性能。结果表明,在钛合金表面成功制备了高硬度、高强度、枝晶状分布的渗氮层。同时,渗氮层内硬度、模量、强度以及应力-应变关系、摩擦系数等力学性能呈现出类似于激光渗氮层内氮元素扩散曲线的非均匀性空间分布规律。硬度和弹性模量之比以及纳米划痕试验结果表明,激光渗氮层的抗磨损性能随深度的增加逐渐降低,摩擦系数随着划入深度的增加,从0.2增加到0.4。

Laser gas nitriding of Ti6Al4V was performed by pulsed Nd：YAG laser.Nanoindentation and nanoscratch instruments were used to quantitatively evaluate the elastic-plastic properties.Results indicate that dendrite structure in the nitriding layer is formed with high hardness,high strength and metallurgical bonding to the titanium alloy substrate.It is found that the hardness,elastic modulus,yield stress and stress-strain responseof the nitriding layer decrease gradually with depth.It is ascribed to the gradient diffusion of nitrogen along depth in the nitriding layer.Meanwhile,the ratios of hardness and elastic modulus by nanaoindentation and the nanoscratch experimentss show that the wear resistance of the nitriding layer deereases along its depth.The friction coefficients increase from 0.2 to 0.4 along depth.