Indentation Response and Structure‐Property Correlation in a Bimodal Ti–6Al–4V Alloy

Abstract

Understanding the deformation behavior of multi-phase alloys under external loading requires careful mechanical characterization of the individual constituent phases at various length scales. The present study first evaluates the elastic moduli and hardness of the microstructural constituents viz. primary a (a p ) and transformed b (secondary a (a s ) plus retained prior b) phases in a bimodal Ti-6Al-4V alloy by nanoindentation using different loads. The bulk mechanical properties of the overall microstructure are then determined by grid wise nano-indentation, as well as micro-indentation. The alloy shows a pronounced indentation size effect; the hardness increases with the decrease in indentation load, or depth of penetration. Assuming an iso-stress condition for individual constituents (a p and transformed b) in the rule of mixture approach, the bulk mechanical properties of the Ti-6Al-4V alloy are reasonably predicted. Such prediction of bulk properties, however, is not possible when a similar calculation is performed using iso-strain condition. The transformed b phase shows disparity between the estimated and experimental values, while considering the a s and b phases individually, on both iso-stress and iso-strain assumptions. From these results, the influence of individual microstructural phases (size, distribution, volume fraction, morphology) and the interfaces between them, is found key in controlling the overall bulk mechanical response of the alloy system. KeywordsNano and micro-indentation, bimodal Ti-6Al-4V, indentation size effect, rule of mixture, iso-stress and iso-strain, grain boundary and interface

Nanomechanical Characterization of the Deformation Response of Orthotropic Ti–6Al–4V

“…[29,30] Furthermore, correlation between the macroscopic and experimentally determined nanomechanical response for this and other alloys is substantially supported by recent research. [31][32][33][34][35][36][37] Therefore, the aim of this research is to characterize the orthotropic elastoplastic response of Ti-6Al-4V at the nanometric length scales by applying a hybrid numerical-experimental method.…”

Microstructure, Corrosion and Mechanical Behavior of 15-5 PH Stainless Steel Processed by Direct Metal Laser Sintering

“…Nevertheless, the properties of the alloys can be best reflected on the variation of hardness, H, estimated using Oliver-Pharr relation (Ref [74][75][76][77]. Accordingly, the mean contact pressure is assessed from a measure of the contact depth of penetration, h c , such that the projected contact area, A, is given by (Ref 76):…”