Abstract
In situ nitridation during laser deposition of titanium-molybdenum alloys from elemental powder blends has been achieved by introducing the reactive nitrogen gas during the deposition process. Thus, Ti-Mo-N alloys have been deposited using the laser engineered net shaping (LENS TM) process and resulted in the formation of a hard α(Ti,N) phase, exhibiting a dendritic morphology, distributed within a β(Ti-Mo) matrix with fine scale transformed α precipitates. Varying the composition of the Ar + N 2 gas employed during laser deposition permits a systematic increase in the nitrogen content of the as-deposited Ti-Mo-N alloy. Interestingly, the addition of nitrogen, which stabilizes the α phase in Ti, changes the solidification pathway and the consequent sequence of phase evolution in these alloys. The nitrogen-enriched hcp α(Ti,N) phase has higher c/a ratio, exhibits an equiaxed morphology, and tends to form in clusters separated by ribs of the Mo-rich β phase. The Ti-Mo-N alloys also exhibit a substantial enhancement in microhardness due to the formation of this α(Ti,N) phase, combining it with the desirable properties of the β-Ti matrix, such as excellent ductility, toughness, and formability.
| Original language | English |
|---|---|
| Pages (from-to) | 7157-7166 |
| Number of pages | 10 |
| Journal | Journal of Materials Science |
| Volume | 47 |
| Issue number | 20 |
| DOIs | |
| State | Published - Oct 2012 |
| Externally published | Yes |
Funding
Acknowledgements This work has been supported by the ISES contract awarded to the University of North Texas by the US Air Force Research Laboratory, AFRL contract number FA8650-08-C-5226, with Dr. Jay Tiley as the program manager. The authors also gratefully acknowledge the Center for Advanced Research and Technology (CART) at the University of North Texas.