Temperature and strain rate dependence of the portevin-le chatelier effect in a rapidly solidified Al alloy

Abstract

The Portevin-Le Chatelier (PL) effect was studied for a rapidly solidified aluminum alloy in a temperature range of 193 to 423 K and a strain rate range of 10~5 to 10~’ s’1. Emphasis was put on the dependence of the critical strain (ɛ c) for the PL effect on temperature (7) and strain rate (ɛ). It is found that the overall ɛc -T-ɛ relation is grouped into two categories: ɛc increases with increasing ɛ but with decreasingT in the low T/high ɛ regime and ɛc increases with increasingT but with decreasing ɛ in the high T/1ow ɛ regime. The underlying dynamic strain aging (DSA) mechanism is discussed to account for the two different yet unified categories by calculating activation energies and by introducing the transition conditions.