Dresden 2017 – scientific programme
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MM: Fachverband Metall- und Materialphysik
MM 22: Poster session I
MM 22.4: Poster
Monday, March 20, 2017, 19:00–20:00, P4
Design of Ti-based alloys with austenitic Ni-Ti nanoprecipitates — •Sascha B. Maisel1, Won-Seok Ko2, Jiali Zhang3, Blazej Grabowski1, and Jörg Neugebauer1 — 1Max-Planck Institut für Eisensforschung, Düsseldorf, Germany — 2Ulsan University, Ulsan, Republic of Korea — 3Massachusetts Insitute of Technology, Cambridge, USA
The properties of Ni-Ti nanoparticles differ from the properties of bulk Ni-Ti, yet they retain their characteristic shape memory effect. Austenitic Ni-Ti nanoprecipitates can be dispersed in metallic matrices and it has been speculated that this may lead to transformation-based strengthening due its intrinsic shape-memory property. Such an approach is considered promising to confer so-called “self-healing” features to alloys. Here, we present a combined experimental and theoretical study of such nanoprecipitates embedded coherently in Ti-V matrices. Using our knowledge of the Ni-Ti-V phase diagram based on a combination of density-functional theory and CALPHAD methods we were able to synthesize such alloys. Preliminary SEM investigations suggest nanoparticles of ≈200 nm can form in Ni-V matrices with ≈45 at. % V. Despite this progress, making samples large enough for mechanical testing remains a challenge. Thus, we study the properties of the compound using three-dimensional atomistic simulations based on the modified embedded atom method. We determine the conditions under which the martensitic transformation of such nanoparticles is triggered, which depends on the size of the particle, the composition of the surrounding matrix, temperature and strain state of the system.