Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2019 Jan 7;12(1):176.
doi: 10.3390/ma12010176.

Mechanical Properties and Microstructure of DMLS Ti6Al4V Alloy Dedicated to Biomedical Applications

Żaneta Anna Mierzejewska  1 , Radovan Hudák  2 , Jarosław Sidun  3
Affiliations

Mechanical Properties and Microstructure of DMLS Ti6Al4V Alloy Dedicated to Biomedical Applications

Żaneta Anna Mierzejewska et al. Materials (Basel). .

Abstract

The aim of this work was to investigate the microstructure and mechanical properties of samples produced by direct metal laser sintering (DMLS) with varied laser beam speed before and after heat treatment. Optical analysis of as-built samples revealed microstructure built of martensite needles and columnar grains, growing epitaxially towards the built direction. External and internal pores, un-melted or semi-melted powder particles and inclusions in the examined samples were also observed. The strength and Young's modulus of the DMLS samples before heat treatment was higher than for cast and forged samples; however, the elongation at break for vertical and horizontal orientation was lower than required for biomedical implants. After heat treatment, the hardness of the samples decreased, which is associated with the disappearance of boundary effect and martensite decomposition to lamellar mixture of α and β, and the anisotropic behaviour of the material also disappears. Ultimate tensile strength (UTS) and yield strength(YS) also decreased, while elongation increased. Tensile properties were sensitive to the build orientation, which indicates that DMLS generates anisotropy of material as a result of layered production and elongated β prior grains. It was noticed that inappropriate selection of parameters did not allow properties corresponding to the standards to be obtained due to the high porosity and defects of the microstructure caused by insufficient energy density.

Keywords: direct metal laser sintering; mechanical properties; porous biomaterials; selective laser melting; titanium alloys.

PubMed Disclaimer

Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Samples: for tensile test (a); dimensions in mm (b) of tensile samples.
Figure 2
Figure 2
Top surface of a vertically built direction (a), lateral surface (b) and top surface of sample sintered with laser beam speed 300 mm/s (c), 500 mm/s (d), 1100 mm/s (e), 1300 mm/s (f).
Figure 3
Figure 3
The influence of scanning speed and energy density on the porosity.
Figure 4
Figure 4
The influence of energy density on the porosity and their morphology: 44 J/mm3 (a), 52 J/mm3 (b), 63 J/mm3 (c), 81 J/mm3 (d), 113 J/mm3 (e), 188 J/mm3 (f), mag. 100×.
Figure 5
Figure 5
Cross-sections perpendicular (a,b) and parallel with deposited layers (c,d) before (a,c) and after (b,d) heat treatment, revealing microstructure of the as built (a,c) and annealed sample (b,d); mag. 100×.
Figure 6
Figure 6
Mechanical properties of Ti6Al4V samples vertically (XZ) and horizontally (XY) oriented to the building direction before (a) and after (b) heat treatment.
Figure 7
Figure 7
Anisotropic properties of samples built with different orientation.
Figure 8
Figure 8
Fracture surface of non-treated (a,b) and heat treated (c–f) vertically (a,c,e) and horizontally (b,d,f) oriented samples; mag. 900× and 1500×.
Figure 8
Figure 8
Fracture surface of non-treated (a,b) and heat treated (c–f) vertically (a,c,e) and horizontally (b,d,f) oriented samples; mag. 900× and 1500×.
Figure 9
Figure 9
Comparison of series and samples hardness.
See this image and copyright information in PMC

References

    1. Albrektsson T., Chrcanovic B., Östman P.O., Sennerby L. Initial and long-term crestal bone responses to modern dental implants. Periodontology. 2017;73:41–50. doi: 10.1111/prd.12176. - DOI - PubMed
    1. Kontis T.C. Modern Implants: Surgical and Injectable. Arch. Facial Plast. Surg. 2016;32:471–472. doi: 10.1055/s-0036-1588012. - DOI - PubMed
    1. Senna P., Antoninha Del Bel Cury A., Kates S., Meirelles L. Surface damage on dental implants with release of loose particles after insertion into bone. Clin. Implant. Dent. Relat. Res. 2015;17:681–692. doi: 10.1111/cid.12167. - DOI - PMC - PubMed
    1. Wan P., Tan L., Yang K. Surface modification on biodegradable magnesium alloys as orthopedic implant materials to improve the bio-adaptability: A review. J. Mater. Sci. Technol. 2016;32:827–834. doi: 10.1016/j.jmst.2016.05.003. - DOI
    1. Novakov T., Jackson M.J., Robinson G.M., Ahmed W., Phoenix D.A. Laser sintering of metallic medical materials—A review. Int. J. Adv. Manuf. Technol. 2017;93:2723–2752. doi: 10.1007/s00170-017-0705-3. - DOI

LinkOut - more resources