Plastic flow mechanisms in microcast aluminium wires

A microcasting process is developed to produce microwires of pure or alloyed aluminium. These wires have a diameter ranging between five and twenty micrometers and have a high aspect ratio, on the order of 50. The wires furthermore are monocrystalline and have a surface roughness around 30 nm. Their monotonic plastic flow, in uniaxial tension, has features similar to those of larger single crystals; however, deformation progresses in these crystals by a series of sudden strain bursts of stochastically distributed intensity. We study the distribution of these strain bursts, and also present results from relaxation tests conducted on such wires, in which we probe the role of thermal activation on the initiation and cessation of dislocational plasticity within samples. Mechanical tests are supplemented with microscopic investigations of the metal substructure evolution that accompanies deformation of the wires.