Time resolved in-situ synchrotron radiation diffraction investigation of grain-growth kinetics in magnetic nanocomposites

Abstract

Abstract. Nanocrystalline powders with nominal composition Co 42 Fe 22 Sm 22 Nb 7 B 4 Cu 2 Ag 1 were synthesized by high-energy ball-milling. In the as-milled state, the alloy specimens consist of nanocrystalline α-(Fe,Co). The formation of hard magnetic Sm 2 Co 17 or Sm 2 Fe 17 phases within the surrounding (Fe,Co) matrix during continuous heating was followed by insitu X-ray diffraction experiments performed at the HASYLAB/DESY synchrotron radiation facility in Hamburg, Germany. The hard magnetic Sm 2 Co 17 nanocrystalline phase forms at temperatures near to 800°C. The temperature evolution of the grain-size distribution was obtained from the integral breadth double-Voigt analysis of the broadening of the (Fe,Co)-matrix X-ray diffraction lines. The kinetics of microstructure coarsening seems to be influenced by grain boundary pinning (drag) effects correlated with the formation of a two-phase microstructure.