Indentation-derived creep response of cast and laser powder bed fused AlSi10Mg alloy: Air temperature

Abstract

Compared with time-consuming conventional uniaxial tensile/compressive creep experiments, depth-sensing indentation testing is considered a reliable, and convenient testing technique to assess the time-dependent plastic deformation of materials in a reasonable time scale. In the present study, we report the ambient (room) temperature indentation creep properties of additively manufactured (i.e., laser-powder bed fused) and cast AlSi10Mg alloy at as-fabricated and different post-fabrication heat treatment states. The indentation creep testing parameters (i.e., dwell time, peak indentation load, and indenter shape) were optimized to adequately represent the creep response (time-displacement) variations for different material conditions. To this end, dual-stage, constant loading rate followed by constant-load holding, pyramidal indentation experiments were performed at a loading rate of 10 mN/s, a peak load of 200 mN, and a dwell time of 400 s. Besides, electron backscattered diffraction was performed to evaluate the manufacturing process (selective laser melted versus cast)/ post-fabrication heat treatment/ texture/ creep properties relationships for the studied AlSi10Mg alloy. Also, the indentation hardness, indentation strain rate sensitivity, indentation creep exponent, and activation volume were analyzed to study and confirm the mechanism of indentation creep. The calculated high values of creep stress exponents (i.e., >10) are attributed to dislocation-reinforcing particle interaction as the controlling mechanism of the creep which agrees with this assumption that AlSi10Mg is indeed an in-situ metal matrix composite with eutectic silicon as the reinforcing particles.

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Micron

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