Titanium and its alloys are known to have inadequate tribological properties excluding these alloys from applications involving interacting surfaces. Introducing a method to improve titanium’s surface hardness will extend the opportunity to use titanium for applications involving wear surfaces. Additive manufacturing of grade 5 titanium with functionally-graded hardness is demonstrated via in-situ gas alloying. To achieve this, argon:nitrogen mixtures are selectively introduced during a laser directed energy deposition process. Control of the concentration and means of nitrogen introduction is found to effect nitrogen uptake, microstructure, resulting hardness, and propensity for cracking. A functionally-graded titanium structure with surface hardness exceeding 600 HV0.3 and without any instances of cracking was produced. Process-structure-property relationships of in-situ, gas-alloyed titanium are analyzed to investigate the limitations of the technology and identify applications.

众所周知，钛及其合金的摩擦学性能不足，将这些合金排除在涉及相互作用表面的应用之外。引入一种提高钛表面硬度的方法将扩大将钛用于涉及磨损表面的应用的机会。通过原位气体合金化证明了具有功能分级硬度的 5 级钛的增材制造。为了实现这一点，在激光定向能量沉积过程中选择性地引入了氩：氮混合物。发现控制氮引入的浓度和方式会影响氮的吸收、微观结构、所得硬度和开裂倾向。产生了表面硬度超过 600 HV0.3 且没有任何开裂的功能分级钛结构。