An aluminum of commercial purity and a directionally solidified Al-Al3Ni eutectic alloy were extruded to obtain  fiber texture. Tensile testings were then performed at room temperature and 500°C with the tensile direction parallel to the fiber axis. Similar to stage I tensile deformation of single crystals, the room temperature flow curve of the pure aluminum and that of the Al-Al3Ni alloy with pure intergranular particles reveal plateau-like flow behavior at the initial stage of yielding. For the latter deformed at 500°C, the flow curve shows superior elongation with ideal plastic behavior following the initial work-hardening stage. The above results are associated with plastic inhomogeneity with which primary slip occurs in limited subgrains and dislocation activities in most subgrains are extremely low or absent. This plastic inhomogeneity can be rationalized by comparing the Taylor factors of primary slip and multiple slip for the subgrains of different misorientations. Also, as discussed in this paper, the influence of the Portevin-LeChatelier effect on the above results can be neglected if it exists.
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