Exploitation of transition temperatures of NiTi- SMA by adjusting SLM parameters

Abstract

Abstract:It is well known that the transition temperatures, e.g. the austenite peak temperature Ap, of NiTi Shape Memory Alloys (SMAs) can be adjusted by changing the alloy composition. This topic recently became more interesting due to the possibilities to produce SMA-parts by additive manufacturing, specifically by Selective Laser Melting (SLM). The potential of new designs and smart structures by so-called 4D-printingwith locally adjusted transition temperatures Appotentially opensup new applicationsand novel temperature-responsive medical devices. This work focuses on the SLM manufacturing parameters exposure time ET(scanning speed) and laser power Pand their impact on the transition temperatureApbeyond the commonly used generic process parameter energy density ED. By systematical variation of process-and scan-parameters, the impact of the P, ET, sample orientation and layer heightLHas well as interdependencies between them have been studied. Awide range of transition temperatures Apbetween -20°C and 70°C has been reached from one starting material by varying ET. These findings potentially allow the manufacturing of smart devices with multi-stage deformation processes in a single 4D-printed part