Speaker
Description
The processing of heterogeneous grain microstructures is a strategy that is commonly used in metallurgy to face the strength-ductility trade-off dilemma. The harmonic concept was first developed by Pr. Ameyama et al. on several metallic materials, including steel [1], CP titanium, and α/β titanium alloys [2], which all show good mechanical behaviors when harmonic-structured. This study applied this design strategy to fabricate harmonic-structured Ti-24Nb-4Zr-8Sn, a biocompatible and low elastic modulus β-metastable titanium alloy.
The powder metallurgy processing route includes low energy mechanical ball milling (BM) of spherical and pre-alloyed powder particles and their densification by Spark Plasma Sintering (SPS). It results in a heterogeneous microstructure composed of a homogeneous 3D network of β coarse grain regions called “core” and α/β dual-phase fine-grain regions called “shell.” A parametric study of the influence of the processing parameters on the alloy’s microstructural features has been led, and a focus was made on the role of BM and SPS duration. Next, the mechanical behavior via shear and compression tests performed on selected microstructures was evaluated, and compared to homogeneous Ti-24Nb-4Zr-8Sn. Finally, the observed macroscopic behavior was discussed in relation to the probable underlying deformation mechanisms.
[1] Z. Zhang, S. K. Vajpai, D. Orlov, et K. Ameyama, « Improvement of mechanical properties in SUS304L steel through the control of bimodal microstructure characteristics », Mater. Sci. Eng. A, vol. 598, p. 106‑113, mars 2014
[2] S. K. Vajpai, M. Ota, Z. Zhang, et K. Ameyama, « Three-dimensionally gradient harmonic structure design: an integrated approach for high performance structural materials », Mater. Res. Lett., vol. 4, no 4, Art. no 4, oct. 2016
| Speaker Country | France |
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