期刊
COMPOSITES PART B-ENGINEERING
卷 222, 期 -, 页码 -出版社
ELSEVIER SCI LTD
DOI: 10.1016/j.compositesb.2021.109059
关键词
Laser powder bed fusion; In situ alloying; beta-Titanium alloys; Functional gradient composite; Layered structures
资金
- Fundamental Research Program of Shenzhen [JCYJ20170412153039309]
- Guangdong Innovative & Entrepreneurial Research Team Program, China [2016ZT06C279]
- Development and Reform Commission of Shenzhen Municipality, China
- Royal Society, UK [RGS\R2\202122, IEC\NSFC\191319]
This study optimized the laser powder bed fusion parameters to fabricate a highly dense metastable beta Ti-12wt% Mo alloy, and found that different laser area energy densities had significant effects on microstructure and mechanical properties. By adjusting the laser parameters, a Ti-Mo functional gradient composite with high compressive yield strength and improved strain hardening capacity was successfully fabricated.
beta-titanium (Ti) alloys combined with high strength and good ductility have attracted extensive research interest for use in many advanced industrial applications. In this study, laser powder bed fusion (LPBF) parameters were firstly optimised to fabricate highly dense metastable beta Ti-12wt% Mo alloy with largely homogeneous structure from low-cost elemental powders. When the laser area energy density (AED) increased to 4 J/mm(2) using the simple scan mode, the refractory Mo powder melted and dissolved into the Ti matrix due to the increased melting pool temperature and increased cycles of remelting. However, when the same high AED was used in the chess scanning mode, keyhole-induced defects emerged along the island boundaries. The laser beam delay (LBD) and island spacing (IS) settings were then optimised to eliminate keyhole defects. Additionally, it is found that using low and high AED (e.g. 1.6 and 4 J/mm(2) respectively), the builds show significantly different microstructure and mechanical properties. In view of this, a Ti-Mo functional gradient composite (FGC) was fabricated via alternating AEDs of 1.6 and 4 J/mm(2) layer-wise. A gradient distribution of alpha '' phase with varied size and quantities across the designed layer boundaries was produced. The Ti-Mo FGC possessed a high compressive yield strength of 1173 (+/- 15) MPa and improved strain hardening capacity. The developed approach demonstrated the potential for the fabrication of FGCs using an in situ alloying based LPBF.
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