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Microstructure evolution and its effect on mechanical response of the multi-phase reinforced Ti-based composites by laser powder-bed fusion.
- Source :
-
Journal of Alloys & Compounds . Apr2019, Vol. 782, p506-515. 10p. - Publication Year :
- 2019
-
Abstract
- Abstract The Ti-based composites reinforced by in-situ formed TiB and TiC particles were successfully produced by laser powder-bed fusion (LPBF) additive manufactured technology using a B 4 C/Ti composite powder mixture, in order to further enhance the mechanical properties of commercially pure titanium (CP-Ti). The effects of applied laser energy density on the microstructure and attendant mechanical properties of the LPBF-processed parts were investigated, and meanwhile, the underlying formation mechanisms of the TiB and TiC particles by LPBF were elucidated. It showed that the whisker-like TiB and near-granular TiC reinforcements were in-situ formed through a laser-induced reaction of Ti-B 4 C system via a diffusion-nucleation-growth mechanism from the melt. The in-situ reinforcements arranged from dendrite to cellular morphology were primarily determined by the thermal convections that transformed from dendrite to annular patterns as a result of the great elevation of temperature gradient between molten Ti liquid and heated B 4 C particles as an increase in the applied laser energy density. The tensile tests revealed that the LPBF-ed Ti-based composites possessed an enhanced tensile strength from 893 ± 5 MPa to 1211 ± 8 MPa and a slightly reduced elongation from 18.1% to 16.8% with the transition of typically fracture morphologies from elongated dimples to equiaxed-ultrafine dimples, respectively, attributed to the combined grain refinement and microstructure strengthening effects. Highlights • Ti-based composites with novel reinforcements were produced through laser powder-bed fusion. • Thermal convection induced by laser energy input is responsible for the arrangement of in-situ TiB-TiC reinforcements. • Composite with dendrite-shaped exhibits a low tensile strength in comparison to that with cellular one. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 09258388
- Volume :
- 782
- Database :
- Academic Search Index
- Journal :
- Journal of Alloys & Compounds
- Publication Type :
- Academic Journal
- Accession number :
- 134687903
- Full Text :
- https://doi.org/10.1016/j.jallcom.2018.12.182