R. Zarnetta, M. Rahim, G. Eggeler, A. Ludwig, Ruhr-University Bochum, Bochum, Germany; R. Takahashi, I. Takeuchi, University of Maryland, College Park, MD; M. L. Young, Ruhr University, Bochum, Germany; J. Frenzel, Ruhr University Bochum, Bochum, Germany; Y. S. CHU, Advanced Photon Source, Argonne National Laboratory, Argonne, IL
This contribution demonstrates how the combinatorial approach for fabrication and characterization of ternary Ti‑Ni‑X shape memory thin film materials libraries can be extended to quaternary Ti‑Ni‑X‑Y systems. Advanced deposition methods based on wedge-type multilayer thin films sputtered from elemental targets yield materials libraries that cover large continuous regions of quaternary systems. Automated temperature-dependent resistance measurements (R(T)) and energy dispersive X-ray analysis (EDX) were applied for the high-throughput characterization of the quaternary composition spreads. Characterization of the crystal structure was carried out using standard X-ray diffraction, as well as synchrotron X-ray microdiffraction at the beamline 2-BM of the Advanced Photon Source, Argonne National Laboratory. Results will be presented for the Ti‑Ni‑Cu‑Pd system, where the phase transformation characteristics were mapped by R(T) for compositions with Ti content close to 50 at.%. A composition region with “zero” thermal hysteresis was found as predicted by James and Zhang (Magnetism and Structure in Functional Materials, Springer, 2005;79:159) based on the general non-linear theory of martensite. We scaled up the thin film results to bulk SMAs using a conventional arc melting method. For the characterization of the phase transformation characteristics of bulk alloys we adopted the alternating current potential drop measurement (ACPD). The functional fatigue properties were investigated by repeated thermal cycling in a differential scanning calorimetry setup. Significantly improved functional stability was found for a quaternary Ti-Ni-Cu-Pd alloy with “zero” thermal hysteresis.
Summary: The accelerated discovery, development and optimization of materials using combinatorial materials science approaches led to improved understanding of structure-property-relationships for thin film and bulk materials over the last twenty years. Today, scaling up combinatorial thin film results to bulk materials bridges and further accelerates the discoveries in both fields. Here, using thin-film composition spreads, we have mapped the thermal hysteresis and the lattice parameters of quaternary shape memory alloys (SMAs) using high-throughput characterization technique and discovered alloys with zero thermal hysteresis, as predicted by the general non-linear theory of martensite (GNLTM). We scaled up the thin film results to bulk SMAs by adopting the alternating current potential drop measurement (ACPD) for the characterization of the phase transformation properties for bulk alloys. Their functional fatigue properties were investigated by repeated thermal cycling. Significantly improved functional stability was found for the quaternary Ti-Ni-Cu-Pd alloy, highlighting the significance of the GNLTM.
