Title of article :
Nanocrystalline Fe–C alloys produced by ball milling of iron and graphite Original Research Article
Author/Authors :
Y.Z. Chen، نويسنده , , A. Herz، نويسنده , , Y.J. Li، نويسنده , , C. Borchers، نويسنده , , P. Choi، نويسنده , , D. Raabe، نويسنده , , R. Kirchheim، نويسنده ,
Issue Information :
دوهفته نامه با شماره پیاپی سال 2013
Pages :
14
From page :
3172
To page :
3185
Abstract :
A series of nanocrystalline Fe–C alloys with different carbon concentrations (xtot) up to 19.4 at.% (4.90 wt.%) are prepared by ball milling. The microstructures of these alloys are characterized by transmission electron microscopy and X-ray diffraction, and partitioning of carbon between grain boundaries and grain interiors is determined by atom probe tomography. It is found that the segregation of carbon to grain boundaries of α-ferrite can significantly reduce its grain size to a few nanometers. When the grain boundaries of ferrite are saturated with carbon, a metastable thermodynamic equilibrium between the matrix and the grain boundaries is approached, inducing a decreasing grain size with increasing xtot. Eventually the size reaches a lower limit of about 6 nm in alloys with xtot > 6.19 at.% (1.40 wt.%); a further increase in xtot leads to the precipitation of carbon as Fe3C. The observed presence of an amorphous structure in 19.4 at.% C (4.90 wt.%) alloy is ascribed to a deformation-driven amorphization of Fe3C by severe plastic deformation. By measuring the temperature dependence of the grain size for an alloy with 1.77 at.% C additional evidence is provided for a metastable equilibrium reached in the nanocrystalline alloy.
Keywords :
thermodynamics , Fe–C alloy , Nanocrystalline materials , Segregation , Mechanical alloying
Journal title :
ACTA Materialia
Serial Year :
2013
Journal title :
ACTA Materialia
Record number :
1146963
Link To Document :
بازگشت