Ab initio investigation of the martensitic phase transitions in ternary high temperature shape memory alloys PdxNi0.5-xTi0.5

Publication Date

6-1-2024

Document Type

Article

Publication Title

Physical Review Materials

Volume

8

Issue

6

DOI

10.1103/PhysRevMaterials.8.063605

Abstract

High temperature (>100∘C) shape memory alloys (HTSMAs) are needed for devices in aerospace, automotive, manufacturing, and other sectors of industry, but the available binary HTSMAs are few, posing a limitation to these devices' operating temperatures. One promising approach is to alloy a binary with other elements to tune its martensitic transition temperature (MTT). There exist numerous combinations of metals to form ternaries, quaternaries, etc., and the martensitic phase transitions in these multicomponent SMAs are more complicated than those in binaries. In this work, we studied the martensitic phase transitions in PdxNi0.5-xTi0.5 ternaries using ab initio methods. Based on energy calculations we find that the behavior of energy vs monoclinic angle of PdxNi0.5-xTi0.5 is substantially different from those of binary end members, except for very small x. The energetic analysis suggests that the martensite phase is monoclinic for x≲0.1 and orthorhombic for x≳0.1. Using the ab initio molecular dynamics simulations and thermodynamic integration, we calculated MTT and latent heat vs Pd content x and our theoretical results are in good agreement with measured data. Since relatively small supercells were used in our dynamic simulations, the present first-principles approach is both efficient and accurate and we expect it to become a useful tool in the search for multicomponent HTSMAs with desirable properties.

Funding Sponsor

Aeronautics Research Mission Directorate

Department

Chemical and Materials Engineering

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