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Titanium alloys elaboration with superelastic properties for cladding tests implants – ELASTICITE


Titanium alloys elaboration with superelastic<br />properties for cladding tests implants

New designs and manufactures of dental and joint metal implants

The world market of the implantable medical device, in particular of the dental, Maxillofacial, articular prosthesis, and related equipment is strong annual growth. It is the result of better control of the surgical<br /> Act. At the same time, in this context, the ageing of the population of<br /> European countries increases demand and boosts the markets. The <br />installation of some joint implants is progressing at a nearby rate of <br />10% year. The project is positioned on this market of products with high added value in contributing innovations to better quality of life of the patient. It is the flexibility of the development process that <br />allows the design and manufacture of implants in small series, better <br />yet customized, to deal with unique situations such in infant surgery <br />for example.<br />The association of an alloy with superelastic properties to the process<br />CLAD allows to consider the reduction of the deviation of stress of bone in the implant.<br />The main causes of loosening of joint implants and dental at the origin of the review can be summarized as follows:<br />(1) an osteo poor integration due to the characteristics of the <br />materials on the surface of the implant, but also of the quality of the <br />bone material, an anchorage area little active in the interface;<br />(2) an 'anatomical difference' between the constitution of the patient <br />and the geometry and the size of the implant retained;<br />(3) mechanical stress to the bone-implant interface mainly due to <br />differences in mechanical behaviour (elasticity) metal implant / bone.<br />The project intends to explore new ways of investigation to rethink <br />the design and the manufacture of implants in attempting to find <br />solutions to points 2 and 3 above.

The innovations expected reside in:
-the transformation of selected alloy powder, first technological lock;
- the complete characterization of the alloy after transformation into
powder, then remelting under laser beam (process CLAD) to verify its
adequacy to the applications;
-the proposal for a new joint implants designs tailor-made for the
patient's anatomy and the technical requirements of processing methods.
It is the atomization under inert gas (Ar) used for the obtaining of the
The characterizations after transformations will be:
-metallurgical (XRD, metallography, SEM);
-mechanical (tensile, flexural yield strength and ultimate strength,
mechanical fatigue, nano-indentation for the measurement of the moduli of elasticity in the interface region to the os, scratch an
-biological (cell cultures) to check the biocompatibility after

As of October 01, 2013, the manufacture of the alloy with the expected characteristics used to initiate its transformation in powder additive manufacturing CLAD process-compatible was performed.
At the same time, the digital 3D modeling of charge transfer from
the implant to bone must be refined to propose in June 2014, the
manufacture of a demonstrator using the properties expected of
the alloy in a geometry optimized anatomically.

Where processing into powder would be a blocking point, other avenues of research are the study so as to ensure the possibility of a demonstrator
at the end of project. The development of alloy under the laser beam
from a dosage accurate mixing of powders, as mentioned in the initial
scientific dossier, is a possible opening.
With the help of surgeons associated with the consortium, the
demonstrator will take the form of a femoral stem of a total hip replacement.

The date of October 01, 2013, the consortium has not enough studying time to propose scientific publications.

In this project, the consortium wishes to develop joint prostheses of new generation made of a new titanium alloy, shaped by a laser additive building (CLAD® process, see description in appendix). The innovative combination of the TiNb titanium alloy specific properties and CLAD® process will substantially reduce the source of prostheses loosening.
The metastable titanium alloys developed by LEM3 partner exhibit a Young modulus much closer to that of bone, compared to the Ti alloys currently in use. These new biomimetic alloys are made from elements considered as bio-inerts (Nb, Zr, Y, N, Si). Different optimized microstructures based on thermo-mechanical treatments have resulted in a very low Young’s modulus (20 – 40 GPa) and high resistance.
The CLAD® process allows shaping parts that conventional process (e.g., forging, casting) cannot; its flexibility enables the manufacturing of biomimetics shapes applicable to individual parts close to the morphological parameters of patients.
The major technological advance relies in the metallurgical behavior of the alloy TiNb considered. Indeed, it is mandatory to validate the remained material properties in the different processing steps (pre-alloy ingot, atomizing, CLAD development of structure, etc.). Volumes and surfaces will therefore be exhaustively characterized (metallurgical, mechanical, electrochemical and biological) as there is currently no data available in the literature.
The second important aspect developed in this project concerns the multi-materials concept. The alternative implementation is to start with a smaller piece of a standard Ti alloy manufactured by conventional routes, particularly in the metaphysal portion of a joint implant. Therefore, only additive forms manufactured with CLAD® will fill the volume in the medullary canal, adapting the prosthesis to the patient’s morphology, limiting hence the TiNb volume only to the parts in contact with bone.
In order to achieve this goal, the additive building with TiNb alloy start on a Ti conventional alloy part. The understanding, control and optimization of how the intermediate layers are built with respect to specific metallurgical behaviors will be studied and fully characterized.
This program aims at proposing a new concept for developing customized prostheses, leading to a major change in the current industrial scheme. The concept will promote an increase in the lifetime of the implant and a better quality of life of patients, because of an enhanced osteointegration: gradient in properties, biomimetic properties, localized functional surfaces.

Project coordination

Pierre MILLE (INSA de Strasbourg, LGeCO) – pierre.mille@insa-strasbourg.fr

The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.


IRTES / LERMPS Institut de Recherche sur les Transports, l'Energie et la Société /Laboratoire d'Etudes et de Recherche sur les Matériaux, les Procédés et les Surface
INSA de Strasbourg, LGeCO INSA de Strasbourg, LGeCO
LEM3 Laboratoire d'Etudes des Microsctructures et de Mécanique des Matériaux

Help of the ANR 318,864 euros
Beginning and duration of the scientific project: February 2013 - 24 Months

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