Probing martensitic transformation, kinetics, elastic and magnetic properties of Ni2-Mn1.5In0.5Co alloys

Composition-Dependent of 6 M Martensite Structure and Magnetism in Cu-Alloyed Ni-Mn-In-Co by First-Principles Calculations

“…A larger atomic radius or magnetism leads to a larger lattice constant. In comparison with the lattice constant of the A phase in the Ni 21 Mn 18 In 6 Co 3 alloy (5.937 [12]), the lattice constant increases slightly as the non-magnetic Cu replaces Ni or Co (as shown in Fig. 5).…”

“…A 48-atom supercell is established, and the Ni 21 Mn 18 In 6 Co 3 hereafter is adopted to represent the alloy composition. Ni 21 Mn 18 In 6 Co 3 alloy is chosen since it has a magneto-structural transformation including a 6 M martensite structure, the phase transformation temperature near room temperature, and a relatively high ∆M based on the information in the literature [12]. The correlations of the specific compositions between this work and the standard notations are listed in Table 1.…”

“…As is known to all, the ∆T Hys is closely related to the geometrical incompatibility between the A phase and martensite phase [28,29]. The ∆T Hys is usually described qualitatively [12] is also represented as a reference by lattice mismatch, transformation strain ε in the tetragonal phase, and volume changes between the parent and martensitic phases [30]. From the expression for the transformation strain, i.e., ε = (c/a) 2/3 -1, it is clear that the c/a ratio is proportional to ε, and the ∆T Hys increases as the ε increases [31,32].…”

“…So far, the most successful way to tune the martensitic transformation, ∆M, and ∆T Hys for Ni-Mn-In alloys is composition alloying. Many researchers have demonstrated that the addition of Co can lead to a significant increase in the magnetization of the parent phase [11,12]. Moreover, the first-principles calculations indicate that Co preferentially occupies the Ni sublattice directly [12].…”

“…Many researchers have demonstrated that the addition of Co can lead to a significant increase in the magnetization of the parent phase [11,12]. Moreover, the first-principles calculations indicate that Co preferentially occupies the Ni sublattice directly [12]. However, an unavoidable problem is a significant increase in ∆T Hys with the substitution of Ni by Co. On the contrary, the Cu addition can reduce the ∆T Hys [10,13,14] and Cu atoms have been identified as preferentially occupying excess Mn sites by theoretical calculations [15].…”