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Abstract

TiTa-based alloys are promising candidates as high-temperature shape memory alloys (HTSMAs) for actuators and superelastic applications. The shape memory mechanism involves a martensitic transformation between the low-temperature α'' phase (orthorhombic) and the high- temperature β phase (body-centered cubic). In order to prevent the degradation of the shape memory effect, TiTa needs to be alloyed with further elements. However, this often reduces the martensitic temperature M_s , which is usually strongly composition dependent. The aim of this work is to analyze how the addition of a third element to TiTa alloys affects M_s by means of electronic structure calculations. In particular, it will be investigated how alloying Al to TiTa alters the relative stability of the α'' and β phases. This understanding will help to identify new alloy compositions featuring both a stable shape memory effect and elevated transformation temperatures.