Mechanical Properties of Spark Plasma Sintering-Processed Pure Ti and Ti-6Al-4V Alloys: A Comparative Study between Harmonic and Non-Harmonic Microstructures

Tarik Sadat,Eric Markiewicz,Herve Morvan,Laurent Dubar,Kyohei Hayashi,Kei Ameyama,Maxence Bigerelle,Gregory Haugou,Guy Dirras

doi:10.3390/compounds1010005

Abstract

Microstructure characteristics and compressive property relationships of so-called harmonic (composed by fine and coarse grains) and conventional pure titanium (Ti) and Ti-6Al-4V alloy processed by powder metallurgy route are presented in the present work. Electron backscatter diffraction (EBSD) analysis was performed to characterize the as-processed microstructures. The harmonicity structure of selected samples is described, and relevant EBSD maps are presented. The bulk samples’ hardness is reported, along with compressive responses at quasi-static and intermediate strain rates, ranging from 0.005 s−1 to 16 s−1. The strain rate sensitivity of these metallic samples is discussed, and the benefits in terms of mechanical properties of the harmonic microstructures compared with the non-harmonic conventional ones are highlighted. Finally, a modified Johnson–Cook model was shown to predict fairly the experimental results.

Highlights

Ti and Ti-6Al-4V alloys are widely used in several fields as functional materials due, for example, to their low density and good corrosion resistance [1,2,3]
Several constitutive material models were proposed in the literature (Johnson–Cook [19], Bammann–Chiesa–Johnson [42], Zerilli–Armstrong [43], Bodner–Partom [44] models . . . ). We examined two such phenomenological models, namely, the Johnson–Cook (JC) model [45] and a modified Johnson–Cook (MJC) model [46], which were developed for general metals
Homogeneous and harmonic structure-designed Pure Ti and Ti-6Al-4V alloys were studied in this work

Summary

Introduction

Ti and Ti-6Al-4V alloys are widely used in several fields (aeronautics, biomedical applications, nuclear energy) as functional materials due, for example, to their low density and good corrosion resistance [1,2,3]. An increase of the mechanical resistance and/or the flow stress of metals leads quite often to a decrease of the ductility. To avoid such loss, several approaches were considered such as severe plastic deformation (SPD) techniques [9] or combining extrusion machining and heat treatment [10]. SPS sintering will consolidate all of the powder by creating an interconnected network of the different particles’ shells. This mechanism leads to a so-called harmonic structure [16,17,18,19]

Methods

Results

Conclusion