In this work, a Ni-alloy Deloro-22 was laser-deposited on a Ti–6Al–4V bar substrate with multiple sets of laser processing parameters. The purpose was to apply laser surface modification to synthesize different combinations of ductile TiNi and hard Ti2Ni intermetallic phases on the surface of Ti–6Al–4V in order to obtain adjustable surface properties. Scanning electron microscopy, energy dispersion spectroscopy, and X-ray diffraction were applied to reveal the deposited surface microstructure and phase. The effect of processing parameters on the resultant compositions of TiNi and Ti2Ni was discussed. The hardness of the deposition was evaluated, and comparisons with the Ti–6Al–4V bulk part were carried out. They showed a significant improvement in surface hardness on Ti–6Al–4V alloys after laser processing, and the hardness could be flexibly adjusted by using this laser-assisted surface modification technique.
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In situ design of advanced titanium alloy with concentration modulations by additive manufacturing
Additive manufacturing is a revolutionary technology that offers a different pathway for material processing and design. However, innovations in either new materials or new processing technologies can seldom be successful without a synergistic combination. We demonstrate an in situ design approach to make alloys spatially modulated in concentration by using laser-powder bed fusion. We show that the partial homogenization of two dissimilar alloy melts—Ti-6Al-4V and a small amount of 316L stainless steel—allows us to produce micrometer-scale concentration modulations of the elements that are contained in 316L in the Ti-6Al-4V matrix. The corresponding phase stability modulation creates a fine scale–modulated β + α′ dual-phase microstructure that exhibits a progressive transformation-induced plasticity effect, which leads to a high tensile strength of ~1.3 gigapascals with a uniform elongation of ~9% and an excellent work-hardening capacity of >300 megapascals. This approach creates a pathway for concentration-modulated heterogeneous alloy design for structural and functional applications.
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- Award ID(s):
- 1923929
- NSF-PAR ID:
- 10326081
- Date Published:
- Journal Name:
- Science
- Volume:
- 374
- Issue:
- 6566
- ISSN:
- 0036-8075
- Page Range / eLocation ID:
- 478 to 482
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1126/science.abj3770
