The Thermal Transformation Arrest Phenomenon in NiCoMnAl Heusler Alloys

Abstract

In this report, we present findings of systematic research on NiCoMnAl alloys, with the purpose of acquiring a higher thermal transformation arrest temperature (T A ). By systematic research, T A in the NiCoMnAl alloy systems was raised up to 190 K, compared to the highest T A of 130 K in NiCoMnIn. For a selected alloy of Ni 40 Co 10 Mn 33 Al 17 , magnetization measurements were performed under a pulsed high magnetic field, and the critical magnetic field-temperature phase diagram was determined. The magnetic phase diagram for Ni 50−x Co x Mn 50−y Al y was also established. Moreover, from the discussion that the formerly called "kinetic arrest phenomenon" has both thermodynamic and kinetic factors, we suggest a terminology change to the "thermal transformation arrest phenomenon".

Magnetic Field-Induced Reverse Martensitic Transformation and Thermal Transformation Arrest Phenomenon of Ni41Co9Mn39Sb11 Alloy

“…Thus, the approach of dμ0H0/dT to zero means that ΔS becomes zero. Similar behavior has been observed in Ni-Co-Mn-In [5], Ni-Mn-In [16,17], Ni-Co-Mn-Sn [19], Ni-Co-Mn-Ga [20] and Ni-Co-Mn-Al [21][22][23]. The temperature at which dμ0H0/dT approaches zero was previously termed kinetically arrest temperature.…”

“…Basically, the driving force of the thermal transformation, ΔG, can be expressed by ΔG ≈ ΔS· ΔT, where ΔT means supercooling. Therefore, the cessation of the transformation when ΔS = 0 is caused by the thermodynamic origin and the phenomenon should be named "thermodynamic arrest" [23,35]. The thermal transformation arrest temperature differs for different compositions and/or alloy systems, such as 150 K in Ni45Co5Mn36.7In13.3 [5], 40 K in Ni45Co5Mn30Al20 [21], 160 K in Ni45Co15Mn32.5Al17.5 [23] and 50 K in the present Ni41Co9Mn39Sb11 alloy.…”

“…Recently, it has been reported that a thermal transformation arrest phenomenon is observed in Ni-Mn-In [16,17], Ni-Co-Mn-In [5,18], Ni-Co-Mn-Sn [19], Ni-Co-Mn-Ga [20] and Ni-Co-Mn-Al [21][22][23] alloys, thermally induced martensitic transformation being interrupted below a certain temperature during the magnetic field cooling process, and the parent phase remaining even at the low temperature. The characteristic temperature is called the thermal transformation arrest temperature and is defined as the point where the transformation is interrupted and does not proceed with further cooling.…”

“…On the other hand, transformation hysteresis in the magnetic field becomes larger at lower temperature. These behaviors are common to the above NiMn-based shape memory alloys showing the thermal transformation arrest phenomenon, and the temperature dependence of the magnetic field hysteresis has been examined by dividing it into two parts, i.e., a thermally activated term and an athermal term [17,18,22,23]. It has been considered that the components of these terms are different in different alloy systems, such as between Ni-Co-Mn-In and Ni-Co-Mn-Al and that the difference would originate in the different energy barriers related to the thermal activations [22,23].…”

Thermodynamics and Kinetics of Martensitic Transformation in Ni-Mn-based Magnetic Shape Memory Alloys

“…2.3(c). In quaternary systems such as Ni-Co-Mn-In [58,65,66,[97][98][99][100][101], Ni-Co-Mn-Sn [15,101,102], Ni-CoMn-Sb, [101,103,104], Ni-Co-Mn-Al [17,46,[105][106][107] and Ni-Co-Mn-Ga [16,[108][109][110], the same relationship of ΔM as well as MFIT have been found. It should be noted that in most of the above cited studies, magnetization was monitored for the detection of MFIT.…”