TY - JOUR

T1 - The Effect of Local Arrangement of Excess Mn on Phase Stability in Ni–Mn–Ga Martensite

T2 - An Ab Initio Study

AU - Zelený, Martin

AU - Heczko, Martin

AU - Janovec, Jozef

AU - Holec, David

AU - Straka, Ladislav

AU - Heczko, Oleg

N1 - Publisher Copyright: © 2019, ASM International.

PY - 2020/3/1

Y1 - 2020/3/1

N2 - The effect of excess Mn on the stability of modulation and elastic properties was investigated using ab initio electronic structure calculations in Ni–Mn–Ga magnetic shape memory alloy. We used the structure of four layered modulated martensite known as 4O to describe modulation of the martensitic lattice. We found that elastic properties of stoichiometric 4O martensite are very similar to elastic properties of 10M martensite reported in previous calculations. The modulated structure becomes less stable than nonmodulated martensite above 3 at.% of excess Mn which corresponds very well to experimental observation at low temperature. Elastic properties of NM martensite are not significantly affected by Mn content nor local arrangements of Mn-excess atoms. We also found that Mn-excess atoms prefer occupation of distant positions for low Mn-excess composition. The occupation of closest position is preferred for alloys with higher content of Mn.

AB - The effect of excess Mn on the stability of modulation and elastic properties was investigated using ab initio electronic structure calculations in Ni–Mn–Ga magnetic shape memory alloy. We used the structure of four layered modulated martensite known as 4O to describe modulation of the martensitic lattice. We found that elastic properties of stoichiometric 4O martensite are very similar to elastic properties of 10M martensite reported in previous calculations. The modulated structure becomes less stable than nonmodulated martensite above 3 at.% of excess Mn which corresponds very well to experimental observation at low temperature. Elastic properties of NM martensite are not significantly affected by Mn content nor local arrangements of Mn-excess atoms. We also found that Mn-excess atoms prefer occupation of distant positions for low Mn-excess composition. The occupation of closest position is preferred for alloys with higher content of Mn.

UR - http://www.scopus.com/inward/record.url?scp=85076309442&partnerID=8YFLogxK

U2 - 10.1007/s40830-019-00247-0

DO - 10.1007/s40830-019-00247-0

M3 - Article

VL - 6.2020

SP - 35

EP - 44

JO - Shape Memory and Superelasticity

JF - Shape Memory and Superelasticity

SN - 2199-3858

IS - 1

ER -