Abstract
Martensitic transformation with good structural compatibility between parent and martensitic phases are required for shape memory alloys (SMAs) in terms of functional stability. In this study, first-principles-based materials screening is systematically performed to investigate the intermetallic compounds with the martensitic phases by focusing on energetic and dynamical stabilities as well as structural compatibility with the parent phase. The B2, D03, and L21 crystal structures are considered as the parent phases, and the 2H and 6M structures are considered as the martensitic phases. In total, 3384 binary and 3243 ternary alloys with stoichiometric composition ratios are investigated. It is found that 187 alloys survive after the screening. Some of the surviving alloys are constituted by the chemical elements already widely used in SMAs, but other various metallic elements are also found in the surviving alloys. The energetic stability of the surviving alloys is further analyzed by comparison with the data in Materials Project Database (MPD) to examine the alloys whose martensitic structures may cause further phase separation or transition to the other structures.
Highlights
Shape-memory alloys (SMAs) constitute an important class of materials in industrial use because of their shape-memory effect and pseudoelasticity.[1]
Some reports have found that better structural compatibility between the parent and the martensitic phases results in smaller thermal hysteresis, which gives better functional stability.[13,14]
Most of them have been mainly focused on the properties of the specific shape memory alloys (SMAs), such as the crystal and electronic structures of the martensitic structures,[23,24,25] the transformation path and energy profile of the martensitic transformation,[23,26,27] and the phase diagram obtained by quasi-harmonic approximation.[28]
Summary
Shape-memory alloys (SMAs) constitute an important class of materials in industrial use because of their shape-memory effect and pseudoelasticity.[1]. Some reports have found that better structural compatibility between the parent and the martensitic phases results in smaller thermal hysteresis, which gives better functional stability.[13,14] We can expect that appropriate energy difference and good structural compatibility between the parent and the martensitic phases are essential factors when we try to design SMAs. We can adjust working temperature and functional stability of SMAs by replacing their constituent elements with others. The working temperature of Ni–Ti alloys can be much increased to the range of 400–1200 K by the total or partial replacement of Ni and Ti with the same group elements, namely Pd or Pt15,16 and Zr or Hf,[17] respectively These reports imply that the martensitic phases become energetically more stable than the parent phases at low temperature by replacing constituent elements. Greeley et al.[21] have reported the binary surface alloys to show a good electrocatalytic property
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