Regensburg 2007 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 20: Poster session
MM 20.54: Poster
Dienstag, 27. März 2007, 14:45–18:00, Poster C
Microstructure Characterization of Cu2MnAl Heusler-Type Alloys using SEM-EBSD and TEM — Tien Hung Luu1,3, Huy Dan Nguyen2, Vong Vo2, •Steffen Schulze3, and Michael Hietschold3 — 1Department of Physics, Vinh University, Nghean, Vietnam — 2Institute of Materials Science, VAST, Hanoi, Vietnam — 3Institute of Physics, TU Chemnitz, Chemnitz, Germany
Cu2MnAl heusler-type alloys prepared by the melt-spinning show soft magnetic behavior with a coercivity less than 1.6 kA/m and a Curie temperature as high as 600 K and after annealing a large negative magnetoresistance of more than 4%. In this work, we report microstructure investigations of these Cu2MnAl heusler alloys as-quenched and after annealing at 773 K for 24 hours using Electron Backscattered Diffraction (EBSD), Energy Dispersive X-ray Analysis (EDX), Selected Area Electron Diffraction (SAED) and High Resolution Transmission Electron Microscopy (HRTEM). The results show that the as-quenched sample is composed of Cu2MnAl in the fcc structure L21 only. These crystallites are of extremely elongated shape with sizes ranging between 1 to 3um in width and 5 to 15 um in length. After annealing we found two crystalline phases. The predominating one is still of L21 structure with grain sizes from 2 to 7 um but there is a Mn-rich phase too appearing in a wide variety of grain sizes. Some of them range between 10 and 20 nm and others are as big as 1 um in diameter. The appearance of these crystalline phases in the ribbons take essential effect on the magnetic and magnetoresistance properties.