The Twinning Microstructure and Damping Behavior in Mn–30Cu (at%) Alloy

Abstract

The twin boundary damping peak and the transformation damping peak constitute the temperature dependent damping behavior in Mn-Cu alloys. In order to observe the effects of twinning microstructure on the twin boundary damping behavior, a Mn-30 at%Cu alloy was finally treated by furnace cooling (FC) and aging after water-quenching (AG), respectively. Regular twin bands with the similar widths along some {101} twin boundary were observed in FC treated condition, while intersected twin bands with pointed fronts belonging to different {101} twin boundaries occurred in the AG treated specimens. Meanwhile, the twin boundary damping features were obtained based on dynamic mechanical analyzer (DMA) measurement, and increased activation energy and decreased peak damping capacity were found in the AG treated alloy. The distortion state of the interfaces enclosing the decomposed nanometer regions was considered to influence the twinning microstructure formation and hence alter the damping features of the twining microstructure.

Mobility of Twin Boundaries in Fe-Pd-Based Ferromagnetic Shape Memory Alloys

“…This type of hysteretic behaviour is not different from that described by in terms of dislocation break away. 14,17) Cu-Al-Ni 18) , Ni-Mn-Cu 19) and Mn-Cu 20) show a relaxation peak related to the variants movement and in these cases the activation energy can be determined from the frequency dependence of the peak temperature. In contrast, in Ni 2 MnGa, where a relaxation peak related to variants movement could not be found, Gavriljuk et.…”

EBSD Characterization of the Twinning Microstructure in a High-Damping Mn–Cu Alloy

“…As shown in the figure, the two characteristic angles between the two sets of intersecting {113} bands are 144. 4 and 144.95 for the (001)[010] orientation and 145. 35 and 144.4 for the (100)[010] orientation, respectively.…”

“…2, four equivalent {101} twin boundaries that appear in the intersecting or parallel arrangement within each crystal grain have been observed in Mn-Cu alloys. 4,5) On the other hand, the main damping peak observed in Mn-Cu alloys occurs at nearly the same temperature irrespective of the composition of the alloy and it shifts to higher temperatures at higher vibration frequencies.…”

“…The twinning microstructure of Mn-Cu alloys has generally been observed and analyzed by means of transmission electron microscopy (TEM). 4,7,8) However, it appears to be difficult to apply TEM to obtain statistical results on the spatial configuration of the In the present work, EBSD analysis was applied to a Mn-Cu alloy that shows the typical twinning microstructure at room temperature to identify the statistical features of the twin boundaries in the alloy. The misorientation between the corresponding twinning bands is only about 1 , so this is a challenge to EBSD analysis, although the orientation accuracy of EBSD is claimed to be about 0.5 .…”

Tunable elastic modulus in Mn-based antiferromagnetic shape memory alloys

“…It seems very promising to tune the range of T for dE/dT>0 and realize the wide range of T (>100°C) through controlling MT and magnetic transition in this kind of alloys. Besides high damping property [9], Mn-based alloys have oneway [10], two-way [11] and magnetic field controlling shape memory effects [12] and deserve to be deeply explored as functional devices in future. However, there has no investigation focused on the dE/dT as a function of T during phase transition in martensitic alloys.…”