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    Phase formation, thermal stability and mechanical properties of a Cu-Al-Ni-Mn shape memory alloy prepared by selective laser melting
    (São Carlos : Universidade Federal de São Carlos, 2015) Gargarella, Piter; Kiminami, Cláudio Shyinti; Mazzer, Eric Marchezini; Cava, Régis Daniel; Basilio, Leonardo Albuquerque; Bolfarini, Claudemiro; Botta, Walter José; Eckert, Jürgen; Gustmann, Tobias; Pauly, Simon
    Selective laser melting (SLM) is an additive manufacturing process used to produce parts with complex geometries layer by layer. This rapid solidification method allows fabricating samples in a non-equilibrium state and with refined microstructure. In this work, this method is used to fabricate 3 mm diameter rods of a Cu-based shape memory alloy. The phase formation, thermal stability and mechanical properties were investigated and correlated. Samples with a relative density higher than 92% and without cracks were obtained. A single monoclinic martensitic phase was formed with average grain size ranging between 28 to 36 μm. The samples exhibit a reverse martensitic transformation temperature around 106 ± 2 °C and a large plasticity in compression (around 15±1%) with a typical “double-yielding” behaviour.
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    Laser Powder Bed Fusion Processing of Fe-Mn-Al-Ni Shape Memory Alloy - On the Effect of Elevated Platform Temperatures
    (Basel : MDPI, 2021) Ewald, Felix Clemens; Brenne, Florian; Gustmann, Tobias; Vollmer, Malte; Krooß, Philipp; Niendorf, Thomas
    In order to overcome constraints related to crack formation during additive processing (laser powder bed fusion, L-BPF) of Fe-Mn-Al-Ni, the potential of high-temperature L-PBF processing was investigated in the present study. The effect of the process parameters on crack formation, grain structure, and phase distribution in the as-built condition, as well as in the course of cyclic heat treatment was examined by microstructural analysis. Optimized processing parameters were applied to fabricate cylindrical samples featuring a crack-free and columnar grained microstructure. In the course of cyclic heat treatment, abnormal grain growth (AGG) sets in, eventually promoting the evolution of a bamboo like microstructure. Testing under tensile load revealed a well-defined stress plateau and reversible strains of up to 4%.