文摘
When commercial superplastic aluminium alloys were first under development it was concluded that to be successful the alloy should contain both a solid solution addition and a dispersion of fine, thermally stable dispersoids. In contrast to early beliefs, the present work demonstrates that a simple Al–1 wt. % Zr alloy can exhibit good superplastic performance despite the absence of a solid solution element. The starting material was in the form of 1 mm diameter particles produce via impulse atomisation that conferred a solidification rate 10p>3p> K sp>−1p>. After extrusion consolidation, heat treatment to produce a fine distribution of metastable Al3Zr precipitates, and rolling, the resulting sheet exhibited superplastic ductilities in excess of 500 % at a strain rate of 10p>−1p> sp>−1p>. An EBSD study of the deformation behaviour demonstrated substantial grain refinement resulting from dynamic recrystallisation.