On Order-Disorder ($L2_1 \to B2^\prime$) Phase Transition in Ni$_{2+x}Mn_{1-x}$Ga Heusler Alloys

TL;DR

This study investigates the order-disorder phase transition in Ni$_{2+x}Mn_{1-x}$Ga Heusler alloys, revealing a second-order transition from L2_1 to B2' structure that decreases in temperature with increased Ni content.

Contribution

It provides new insights into the nature and temperature dependence of the L2_1 to B2' phase transition in Ni-rich Ni-Mn-Ga alloys.

Findings

The phase transition is of second order.

Transition temperature decreases with Ni excess.

Transition observed in alloys with x = 0.16 - 0.20.

Abstract

Order-disorder phase transition in Ni$_{2+x}Mn_{1-x}$Ga Heusler alloys has been studied. It was found that the $L2_1 \to B2^{\prime}$ phase transition in Ni2+xMn1-xGa (x = 0.16 - 0.20) Heusler alloys is of second order and the temperature of this transition decreases with Ni excess.