Ultrafine grain sizes were introduced into samples of an Al-3 pet Mg solid solution alloy and a cast Al-Mg-Li-Zr alloy using the process of equal-channel angular (ECA) pressing. The Al-3 pet Mg alloy exhibited a grain size of ∼0.23 μm after pressing at room temperature to a strain of ∼4, but there was significant grain growth when the pressed material was heated to temperatures above ∼450 K. The Al-Mg-Li-Zr alloy exhibited a grain size of ∼ 1.2 yum, and the microstructure was heterogeneous after pressing to a strain of ∼4 at 673 K and homogeneous after pressing to a strain of ~8 at 673 K with an additional strain of ∼4 at 473 K. The heterogeneous material exhibited superplasticlike flow, but the homogeneous material exhibited high-strain-rate superplasticity with an elongation of >1000 pet at 623 K at a strain rate of 10-2 s-1. It is concluded that a homogeneous microstructure is required, and therefore a high pressing strain, in order to attain high-strain-rate superplasticity (HSR SP) in ultrafme-grained materials.
|Number of pages||7|
|Journal||Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science|
|Publication status||Published - 1998|
All Science Journal Classification (ASJC) codes
- Condensed Matter Physics
- Mechanics of Materials
- Metals and Alloys