Relating microstructure to magnetocaloric properties in RE36Tb20Co20Al24 (RE = Gd, Dy or Ho) high-entropy metallic-glass microwires designed by binary eutectic clusters method
Hangboce Yin, Junqiang Wang, Yongjiang Huang, Hongxian Shen, Shu Guo, Hongbo Fan, Juntao Huo, Jianfei Sun
Abstract
The new high-entropy metallic-glasses (HE-MGs) are designed by using Dy and Ho to replace Gd in Gd 36 Tb 20 Co 20 Al 24 alloy based on the binary eutectic clusters method. Compared with the equiatomic Gd 25 Tb 25 Co 25 Al 25 HE-MG, the non-equiatomic RE 36 Tb 20 Co 20 Al 24 (RE = Gd, Dy, or Ho) alloys show better glass-forming ability, which is attributed to the deep binary eutectic compositions used for alloy design. All RE 36 Tb 20 Co 20 Al 24 alloys undergo second-order magnetic transition. An extreme peak value of magnetic entropy change is obtained as 10.3 J kg –1 K –1 (5 T) for the Ho 36 Tb 20 Co 20 Al 24 alloy. In - situ high-energy synchrotron X-ray diffraction was conducted to observe the microstructural difference among non-equiatomic samples at cryogenic temperatures. The results indicate that Gd 36 Tb 20 Co 20 Al 24 alloy possesses a relatively large average value of the dispersion of local clusters at a low-temperature range. This, combined with the critical exponent β close to 0.5 of Gd 36 Tb 20 Co 20 Al 24 alloy, leads to its widest working temperature span among non-equiatomic samples. This work successfully establishes the connection between microstructure and magnetocaloric properties of HE-MGs, which is beneficial for understanding the physical mechanism of the magnetocaloric behaviors of HE-MGs.