Powder Technology, Vol.322, 393-401, 2017
Powder metallurgical processing of low modulus beta-type Ti-45Nb to bulk and macro-porous compacts
Low modulus Ti-45Nb is a promising new alloy for bone implant applications owing to its excellent biocompatibility combined with bone-adapted mechanical performance. The present work demonstrates the applicability of powder metallurgical processing, i.e. hot pressing (HP) and spark plasma sintering (SPS), for the compaction of gas-atomized alloy powder under preservation of the main beta-phase. Additional milling of the gas-atomized powder leads to irregular shapes and is effective for a significant refinement of the beta-phase grains but causes increased oxygen contents. The yield strength of nearly fully dense samples increased from approximate to 450 MPa for samples made from gas-atomized to approximate to 900 MPa for samples made from additionally milled powder while the Young's modulus remains low. Exemplarily, the production of macro-porous Ti-45Nb samples with 30% porosity by means of hot pressing with NaCI as space holder is demonstrated. At this porosity level Young's modulus values <= 5 GPa can be obtained. Also for macro-porous samples the use of additionally milled powder was beneficial for achieving increased strength values of approximate to 140 MPa. Mechanical performance data comparable to those of healthy spongy bone are obtained. (C) 2017 Elsevier B.V. All rights reserved.
Keywords:Beta-Ti alloy;Macro-porous;Hot pressing;Spark plasma sintering;Ultrafine-grained;Space holder method