Robert Zarnetta

Development of multifunctional thin films using high-throughput experimentation methods

Abstract This paper describes the use of thin film high-throughput experimentation methods for the efficient development of multifunctional materials, using Ni – Ti – X and ferromagnetic shape memory alloys as examples. The thin films were fabricated in the form of binary, ternary, and quaternary materials libraries by special magnetron sputter deposition processes. These materials libraries were subsequently processed and characterized by high-throughput experimentation methods in order to relate compositional information with structural and functional properties. For this, appropriate visualization of the data is necessary. Results show that the martensitically transforming regions in ternary thin films are generally larger than was known from literature. Within these regions, the variation of the functional properties can be mapped with respect to the composition and microstructure, and thus the most suitable materials for applications can be effectively selected.

Untersuchungen zum Einfluss der Kornorientierung auf Nanoindentations-Messungen an Reineisen

Kurzfassung Bei Lasten im mN-Bereich und Eindringtiefen im nm-Bereich erlauben Nanoindentations-Versuche die Untersuchung der lokalen mechanischen Eigenschaften einzelner Körner. Dabei ist ein Einfluss der Kornorientierung auf Elastizitäts-Moduli und Härte zu erwarten. In dieser Arbeit wird der Einfluss der Kornorientierung auf Nanoindentations-Messungen an reinem α-Eisen dokumentiert. Einzelne Körner mit <001>-, <101>- und <111>-Oberflächennormalen werden per Rückstreu-Elektronenbeugung identifiziert und anschließend indentiert. Die Kornorientierung hat einen deutlichen Einfluss auf die ermittelten Härtewerte, aber einen vernachlässigbaren Effekt auf richtungsabhängige E-Moduli. Diese Ergebnisse können durch die Art der Aktivierung der Gleitsysteme und durch den komplexen Spannungszustand unter der Indenterspitze erklärt werden und zeigen den Einfluss anisotroper elastischer und plastischer Eigenschaften auf Nanoindentations-Messungen.

Characterization of a Ti64Ni20Pd16 thin film by transmission electron microscopy

Ti-Ni-thin films fabricated by sputter-deposition are applicable in microdevices like: micropumps, microwrappers, and microgrippers [1–5], since they exhibit excellent shape memory effects and good mechanical properties [6]. The addition of a third element like Pd, Pt or Hf increases the transformation temperature. It is already reported that the substitution of Pd for Ni can increase the transformation temperatures of Ti-Ni from approximately room temperature to 800 K [7]. The phase transformation characteristics within the Ti-Ni-Pd system were recently investigated by combinatorial materials science methods [8]. For the first time the complete composition region showing a reversible phase transformation was determined. For non-transforming compositions, e.g. Ti64Ni20Pd16, X-ray diffraction results showed pronounced amounts of Ti2Pd and Ti2Ni precipitates. However the mechanism of how the precipitates might hinder the phase transformation could not be deduced. Therefore a TEM sample of Ti64Ni20Pd16 was cut form the Ti-Ni-Pd composition spread by target preparation methods using a focused ion beam (FIB) system with attached energy dispersive X-ray (EDX) analysis.