Serrated Flow Behavior of Titanium‐Based Composites with Different In Situ TiC Contents

Abstract

Ultrafine-grained b-Ti 70 Nb 30 -matrix composites (TMCs) reinforced by in situ TiC ceramic particles are fabricated by spark plasma sintering of mechanically alloyed blended powders of respective b-Ti 70 Nb 30 and C powders. The results show that the fabricated TMCs with 2.5 vol% (TMC 2.5) and 7.5 vol% (TMC 7.5) in situ TiC particles exhibit almost invariable fracture strength of approximately 2 200 MPa and plastic strain of approximately 46%. To explain these results, the self-organized critical state in dynamics and the power-law distribution are used to investigate the serrated flow behavior of the stress-strain curves for the fabricated TMCs. The larger stress-drop magnitudes, fitted scaling exponents (b), and cut-off stress-drop magnitude (s c ) for the TMC 2.5 are attributed to the larger intershear band (SB) spacing and lower density of SBs. Their interactions resulted from the presence of the in situ TiC particles with lower content. In addition, the larger stress-drop magnitudes before a strain of 20% for the TMC 2.5 are due to the greater moving distance of the SBs, whereas the almost constant stress-drop magnitude after 20% strain for the two TMCs is because of SB interactions induced by the in situ TiC particles. The results obtain provide some insights into fabricating high-performance TMCs by tailoring SBs and their interactions. Fig. 10. Generated SBs and their interactions on the sample surfaces for the TNC 2.5 (a) and (c) and TNC 7.5 (b) and (d) TMCs after plastic strains of 15% (a) and (b) and 30% (c) and (d), respectively.