The Influence of Severe Plastic Deformation on Microstructure and In Vitro Biocompatibility of the New Ti-Nb-Zr-Ta-Fe-O Alloy Composition.

Carmela Gurau,Anisoara Cimpean,Alexandru Dan,Valentina Mitran,Gheorghe Gurau

doi:10.3390/ma13214853

Carmela Gurau, Anisoara Cimpean + Show 3 more

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https://doi.org/10.3390/ma13214853

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Abstract

In this work, severe plastic deformation (SPD) of the newly designed Ti-Nb-Zr-Ta-Fe-O GUM metal was successfully conducted at room temperature using high speed high pressure torsion (HSHPT) followed by cold rolling (CR) to exploit the suitability of the processed alloy for bone staples. The Ti-31.5Nb-3.1Zr-3.1Ta-0.9Fe-0.16O GUM alloy was fabricated in a levitation melting furnace using a cold crucible and argon protective atmosphere. The as-cast specimens were subjected to SPD, specifically HSHPT, and then processed by the CR method to take the advantages of both grain refinement and larger dimensions. This approach creates the opportunity to obtain temporary orthopedic implants nanostructured by SPD. The changes induced by HSHPT technology from the coarse dendrite directly into the ultrafine grained structure were examined by optical microscopy, scanning electron microscopy and X-ray diffraction. The structural investigations showed that by increasing the deformation, a high density of grain boundaries is accumulated, leading gradually to fine grain size. In addition, the in vitro biocompatibility studies were conducted in parallel on the GUM alloy specimens in the as-cast state, and after HSHPT- and HSHPT+CR- processing. For comparative purposes, in vitro behavior of the bone-derived MC3T3-E1 cells on the commercially pure titanium has also been investigated regarding the viability and proliferation, morphology and osteogenic differentiation. The results obtained support the appropriateness of the HSHPT technology for developing compression staples able to ensure a better fixation of bone fragments.

Highlights

In spite of the extensive development and clinical use experienced by the metallic implants during the last decades, the researchers working in the field of biomaterials and biocompatibility are still seeking for the ideal biomaterial designed for a certain biomedical application [1,2,3]
The aim of the present study is to examine the effects of high speed high pressure torsion (HSHPT) severe plastic deformation in conjunction with cold rolling (CR) deformation on the evolution of the Ti-31.5Nb-3.1Zr-3.1Ta-0.9Fe-0.16O alloy microstructure and to assess the preosteoblast response to this newly developed GUM alloy
The high refinement of the microstructure was induced in the first step by the HSHPT severe plastic deformation method

Summary

Introduction

In spite of the extensive development and clinical use experienced by the metallic implants during the last decades, the researchers working in the field of biomaterials and biocompatibility are still seeking for the ideal biomaterial designed for a certain biomedical application [1,2,3] Among these metals, titanium (Ti) and Ti alloys are the excellent option for orthopedic implants due to their high strength, low modulus, high corrosion resistance, light weight and excellent biocompatibility [4,5,6]. Near-α Ti alloys exhibit a very similar crystallographic form to alpha phase alloys at low temperature These alloys acquire some beta phase (5–10%) by heating. These alloys have been suggested to possess higher strength and lower modulus of elasticity than α and (α + β)-type alloys [15,16,17,18,19], excellent corrosion resistance [20,21,22,23,24], enhanced biocompatibility [21,25,26,27,28,29,30,31] and good formability [31,32,33]

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