Analysis on the amplitude of serrated flow associated with the Portevin-LeChatelier effect of substitutional fcc alloys
- National Cheng-Kung Univ., Tainan (Taiwan, Province of China). Dept. of Materials Science and Engineering
The serration of flow curve is a common feature of the Portevin-LeChatelier effect of substitutional fcc alloys. Under the condition that the onset strain of serration decreases with increasing temperature, previous experimental results have shown that the serration stress amplitude, {Delta}{sigma}, increases with increasing strain ({epsilon}) and temperature (T); it decreases with increasing grain size (d) and strain rate ({dot {epsilon}}). A conventional rationalization assumes that {Delta}{sigma} is proportional to the number of solute atoms, N, in dislocation atmospheres, where N is a function of the diffusion coefficient, aging time, and temperature. By adopting this approach and taking into account the effects of strain rate, strain, and grain size, the relation {Delta}{sigma} {proportional_to} [{dot {epsilon}}{sup {minus}1} {epsilon}{sup {beta}(1/2+{gamma})} d{sup {minus}n(1/2+{gamma})} T{sup {minus}1} exp ({minus}Q/kT)]{sup 2/3} is proposed, where Q is the activation energy associated with substitutional diffusion. The proposed model fits well with the experimental data of an Al-3.7 wt pct Mg alloy.
- OSTI ID:
- 271607
- Journal Information:
- Metallurgical Transactions, A, Journal Name: Metallurgical Transactions, A Journal Issue: 6 Vol. 27; ISSN 0360-2133; ISSN MTTABN
- Country of Publication:
- United States
- Language:
- English
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