Influence of grain size on precipitation hardening in melt-spun Sm(Co, Fe, Cu, Zr)$_{\mathrm{z}}$ alloys

ORAL

Abstract

In this work, we have investigated the influence of grain size on precipitation hardening that takes place in 2:17 Sm-Co magnets. An alloy with a nominal composition of Sm(Co$_{0.72}$Fe$_{0.12}$Cu$_{0.13}$Zr$_{0.03})_{7.6}$ was prepared by arc-melting and subsequently melt-spinning. The grain size was controlled by varying the wheel speed from 5 m/s to 50 m/s. The melt-spun ribbons were subsequently isothermally aged at 850 $^{\circ}$C for 3 h followed by slow cooling at 0.7 K/min to 400 $^{\circ}$C. A single 1:7 phase was detected in the as-spun ribbons and the grain size of ribbons estimated by Scherrer's formula was found to decrease gradually with the increasing of the wheel speed from 5 m/s to 50 m/s. After aging, the 1:7 phase was decomposed into Sm$_{2}$(Co,Fe)$_{17}$ and Sm(Co,Cu)$_{5}$ phase. For the 5 m/s ribbon, the coercivity increased drastically form 0.8 kOe to 11.2 kOe. On the other hand, the coercivity of the 35 m/s ribbon showed a little increase from 4.7 kOe to 6.3 kOe. TEM studies are currently under way to study the microstructure as a function of grain size and the results will be reported.

*Work supported by DOE

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Authors

  • Ozlem Koylu-Alkan

    • Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716, USA
    • University of Delaware

  • Weiqiang Liu

    • Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716, USA

  • XiaoCao Hu

    • Department of Materials Science and Engineering, University of Delaware, Newark, Delaware 19716, USA
    • Department of Physics and Astronomy, University of Delaware, 217 Sharp Lab, Newark, DE 19716, United States

  • George Hadjipanayis

    • Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716, USA
    • University of Delaware
    • Department of Physics and Astronomy, University of Delaware, Newark, DE 19716, USA
    • Department of Physics and Astronomy, University of Delaware, 217 Sharp Lab, Newark, DE 19716, United States