In the present work, both the surface chemical contamination and the mechanical alteration of Ti–6Al–4V (Ti64) and Ti–6Al–4V extra low interstitial (Ti64ELI) titanium alloys subjected to superplastic forming (SPF) for the manufacturing of highly customized biomedical prostheses have been investigated. As case study, a cranial implant was considered. The design of the manufacturing process was assisted by a numerical model calibrated on free inflation experimental tests. Glow discharge optical emission spectrometry (GDOES) analyses, nanoindentation tests, and metallographic analyses allowed to relate the mechanical alteration to the oxygen enrichment due to the environmental exposition during processing. While similar diffusion kinetics were found, different oxidation rates were measured in the two investigated alloys. The hardness variation was strictly related to the oxygen content. In order to verify the material biocompatibility, cytotoxicity tests were conducted on the most oxidized part. Results highlighted that the oxygen enrichment due to the manufacturing process did not significantly affect the cells viability.

References

References
1.
Khorasani
,
A. M.
,
Goldberg
,
M.
,
Doeven
,
E. H.
, and
Littlefair
,
G.
,
2015
, “
Titanium in Biomedical Applications—Properties and Fabrication: A Review
,”
J. Biomater. Tissue Eng.
,
5
(
8
), pp.
593
619
.
2.
Niinomi
,
M.
,
2003
, “
Recent Research and Development in Titanium Alloys for Biomedical Applications and Healthcare Goods
,”
Sci. Technol. Adv. Mater.
,
4
(
5
), pp.
445
454
.
3.
Curtis
,
R.
,
Majo
,
D. G.
,
Soo
,
S.
,
Disilvio
,
L.
,
Gil
,
A.
,
Wood
,
R. D.
,
Atwood
,
R.
, and
Said
,
R.
,
2008
, “
Superplastic Forming of Dental and Maxillofacial Prostheses
,”
Dental Biomaterials: Imaging, Testing and Modelling
, Woodhead Publishing, London, pp.
428
474
.
4.
Chandra
,
N.
,
2002
, “
Constitutive Behaviour of Superplastic Materials
,”
Int. J. Non-Linear Mech.
,
37
(
3
), pp.
461
484
.
5.
Lu¨tjering
,
G.
, and
Williams
,
J. C.
,
2007
,
Titanium: Engineering Materials and Processes
,
2nd ed.
,
Springer
, Berlin, pp.
1
442
.
6.
Klose
,
J.
,
Rehtanz
,
E.
,
Rothe
,
C.
,
Eulitz
,
I.
,
Güther
,
V.
, and
Beck
,
W.
,
2008
, “
Manufacture of Titanium Implants
,”
Materwiss Werksttech
,
39
(
4–5
), pp.
304
308
.
7.
Williams
,
D. F.
,
1987
,
Definitions in Biomaterials: Progress in Biomedical Engineering
, Vol.
4
,
Elsevier
,
Amsterdam, The Netherlands
, p.
72
.
8.
Ratner
,
B. D.
,
2011
, “
The Biocompatibility Manifesto: Biocompatibility for the Twenty-First Century
,”
J. Cardiovasc. Transl. Res.
,
4
(
5
), pp.
523
527
.
9.
Sidambe
,
A. T.
,
2014
, “
Biocompatibility of Advanced Manufactured Titanium Implants—A Review
,”
Materials (Basel)
,
7
(
12
), pp.
8168
8188
.
10.
ISO
,
2009
, “
Biological Evaluation of Medical Devices—Part 1: Evaluation and Testing Within a Risk Management Process
,” International Organization for Standardization, Geneva, Switzerland, Standard No.
ISO 10993-1
.
11.
ISO
,
2009
, “
Biological Evaluation of Medical Devices—Part 5: Tests for In Vitro Cytotoxicity
,” International Organization for Standardization, Geneva, Switzerland, Standard No.
ISO 10993-5
.
12.
Pitt
,
F.
, and
Ramulu
,
M.
,
2007
, “
Post-Processing Effect on the Fatigue Behavior of Three Titanium Alloys Under Simulated SPF Conditions
,”
J. Mater. Eng. Perform.
,
16
(
2
), pp.
163
169
.
13.
Zhang
,
T.
,
Liu
,
Y.
,
Sanders
,
D. G.
,
Liu
,
B.
,
Zhang
,
W.
, and
Zhou
,
C.
,
2014
, “
Development of Fine-Grain Size Titanium 6Al–4V Alloy Sheet Material for Low Temperature Superplastic Forming
,”
Mater. Sci. Eng.: A
,
608
, pp.
265
272
.
14.
Hefti
,
L. D.
,
2008
, “
Innovations in the Superplastic Forming and Diffusion Bonded Process
,”
J. Mater. Eng. Perform.
,
17
(
2
), pp.
178
182
.
15.
Comley
,
P. N.
,
2004
, “
Manufacturing Advantages of Superplastically Formed Fine-Grain Ti–6Al–4V Alloy
,”
J. Mater. Eng. Perform.
,
13
(
6
), pp.
660
664
.
16.
Pitt
,
F.
, and
Ramulu
,
M.
,
2004
, “
Influence of Grain Size and Microstructure on Oxidation Rates in Titanium Alloy Ti–6Al–4V Under Superplastic Forming Conditions
,”
J. Mater. Eng. Perform.
,
13
(
6
), pp.
727
734
.
17.
de Moraes
,
T. F.
,
Amorim
,
P. H.
,
Azevedo
,
F. S.
, and
da Silva
,
J. V.
,
2011
, “
InVesalius—An Open-Source Imaging Application
,”
Computational Vision and Medical Image Processing
,” Vol.
405
, Springer, Berlin.
18.
Maravelakis
,
E.
,
David
,
K.
,
Antoniadis
,
A.
,
Manios
,
A.
,
Bilalis
,
N.
, and
Papaharilaou
,
Y.
,
2008
, “
Reverse Engineering Techniques for Cranioplasty: A Case Study
,”
J. Med. Eng. Technol.
,
32
(
2
), pp.
115
121
.
19.
Piccininni
,
A.
,
Gagliardi
,
F.
,
Guglielmi
,
P.
,
Napoli
,
L. D.
,
Ambrogio
,
G.
,
Sorgente
,
D.
, and
Palumbo
,
G.
,
2016
, “
Biomedical Titanium Alloy Prostheses Manufacturing by Means of Superplastic and Incremental Forming Processes
,”
NUMIFORM 2016: The 12th International Conference on Numerical Methods in Industrial Forming Processes
, Troyes, France, July 4–7, Paper No. 15007.
20.
ISO
,
2015
, “
Metallic Materials—Instrumented Indentation Test for Hardness and Materials Parameters—Part 1: Test Method
,” International Organization for Standardization, Geneva, Switzerland, Standard No.
ISO 14577-1:2015
.
21.
Enikeev
,
F. U.
, and
Kruglov
,
A. A.
,
1995
, “
An Analysis of the Superplastic Forming Thin Circular Diaphragm
,”
Int. J. Mech. Sci.
,
37
(5), pp.
473
483
.
22.
Niinomi
,
M.
,
1998
, “
Mechanical Properties of Biomedical Titanium Alloys
,”
Mater. Sci. Eng.: A
,
243
(
1–2
), pp.
231
236
.
23.
Fukai
,
H.
,
Iizumi
,
H.
,
Minakawa
,
K.
, and
Ouchi
,
C.
,
2005
, “
The Effects of the Oxygen-Enriched Surface Layer on Mechanical Properties of ALPHA + BETA Type Titanium Alloys
,”
ISIJ Int.
,
45
(
1
), pp.
133
141
.
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