Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1575179 | Materials Science and Engineering: A | 2014 | 6 Pages |
Abstract
The effects of strain rate, εÌ, and temperature, T, on the occurrence of the Portevin-Le Chatelier (PLC) effect in tensile hot-rolled (HR) and solid-solution treated (SS) β-phase LZ141 magnesium alloy were studied. The HR alloy has an intrinsically higher dislocation density and fewer solute atoms than the SS alloy. This characteristic, in terms of the dynamic strain aging (DSA) mechanism, explains why the PLC effect does not occur in HR alloy for ÎµÌ ranging from 3.33Ã10â4 sâ1 to 6.67Ã10â2 sâ1 but does occur in SS alloy, in which Type B and Type C serrations appear at εÌ=(3.33-6.67)Ã10â3 sâ1 and at εÌ=(3.33-6.67)Ã10â4 sâ1, respectively. The SS alloy exhibits a negative strain rate sensitivity (SRS) at room temperature. The negative SRS also supports the proposition that the DSA mechanism causes the PLC effect. In the study of the effect of T on the occurrence of the serrated flow, for HR alloy at Tâ¤0 °C, Type A serrations were observed. In contrast, in the SS alloy, Type C serrations occurred in the curves at 25 °C and 0 °C, and Type B serrations occurred at â25 °C and â50 °C. These results can also be explained by the DSA mechanism. Large serrated stress variations were found in the tensile curves of SS alloy at â25 °C and â50 °C, but no twinning was found near the fractured surface.
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Authors
S.K. Wu, C. Chien, C.S. Yang, H.Y. Bor,