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A D V A N C E D M A T E R I A L S & P R O C E S S E S | O C T O B E R 2 0 1 9 5 2 Advertise in SMST NewsWire in April and October 2020! SMJ HIGHLIGHTS to the role of dislocations in the shuffling process during the early stage of transformation. We show that the increase of Ta content raises the CRSS more effectively for the case of slip compared to twinning or transformation. The slip stress and twin stress magnitudes increase with an increase in the unsta- ble fault energy ( γ us ) and unstable twinning fault energy ( γ ut ), respectively. In summary, as the Ta composition increases, the difference between martensite/austenite slip resistance and the transformation/twinning stress widens showing the effica- cy of Ta alloying additions (Fig. 2). PROPERTIES OF CU-BASED SHAPE-MEMORY ALLOYS PREPARED BY SELECTIVE LASER MELTING Tobias Gustmann, Uta Kühn, Simon Pauly, Jonadabe M. dos Santos, Piter Gargarella, and Jan Van Humbeeck Two shape-memory alloys with the nominal composi- tions (in wt%) Cu–11.85Al–3.2Ni–3Mn and Cu–11.35Al–3.2Ni– 3Mn–0.5Zr were prepared by selective laser melting (SLM). The parameters were optimized to identify the process win- dow, in which almost fully dense samples can be obtained. Their microstructures were analyzed and correlated with the shape-memory behavior as well as themechanical properties. Suction-cast specimens were also produced for comparison. Mainly, β 1 ′ martensite forms in all samples, but 0.5 wt% of Zr stabilizes the Y phase (Cu 2 AlZr), and its morphology depends on the thermal history and cooling rate. After annealing, the Y phase is primarily found at the grain boundaries hampering grain coarsening. Due to the relative high cooling rates applied here, Zr is mostly dissolved in the martensite in the as-pre- pared samples and it has a grain-refining effect only up to a critical cooling rate. The Zr-containing samples have increased transformation temperatures, and the Y phase seems to be responsible for the jerky martensite-to-austenite transforma- tion. All the samples are relatively ductile because theymostly fracture in a transgranular manner, exhibiting the typical dou- ble yielding. Selective laser melting allows the adjustment of the transformation temperatures and the mechanical prop- erties already during processing without the need of a subse- quent heat treatment (Fig. 3). Fig. 3 — Optical micrograph of the suction-cast Cu–11.35Al–3.2Ni– 3Mn–0.5Zr alloy. The box indicates the region of the sample, which was chosen for an EBSD measurement (see inset). The purple color reflects b 1 ′ martensite, and the green color represents the Y phase. The black regions could not be ascribed to either phase also due to limited pattern quality. 1 4 For information about advertising in SMST NewsWire: Elaine Yusa, Business Development Manager 312.304.1555, elaine.yusa@asminternational.org Current rate card may be viewed online at asminternational.org/mediakit.