Microstructures of tribologically modified surface layers in two-phase alloys
Por:
Figueroa C.G., Ortega I., Jacobo V.H., Ortiz A., Bravo A.E., Schouwenaars R.
Publicada:
1 ene 2014
Resumen:
When ductile alloys are subject to sliding wear, small increments of
plastic strain accumulate into severe plastic deformation and mechanical
alloying of the surface layer. The authors constructed a simple coaxial
tribometer, which was used to study this phenomenon in wrought Al-Sn and
cast Cu-Mg-Sn alloys. The first class of materials is ductile and
consists of two immiscible phases. Tribological modification is observed
in the form of a transition zone from virgin material to severely
deformed grains. At the surface, mechanical mixing of both phases
competes with diffusional unmixing. Vortex flow patterns are typically
observed. The experimental Cu-Mg-Sn alloys are ductile for Mg-contents
up to 2 wt% and consist of alpha-dendrites with a eutectic consisting
of a brittle Cu2Mg-matrix with alpha-particles. In these, the
observations are similar to the Al-Sn Alloys. Alloys with 5 wt% Mg are
brittle due to the contiguity of the eutectic compound. Nonetheless,
under sliding contact, this compound behaves in a ductile manner,
showing mechanical mixing of alpha and Cu2Mg in the top layers and a
remarkable transition from a eutectic to cellular microstructure just
below, due to severe shear deformation. AFM-observations allow
identifying the mechanically homogenized surface layers as a
nanocrystalline material with a cell structure associated to the sliding
direction.
Filiaciones:
Figueroa C.G.:
Departamento de Materiales y Manufactura, Facultad de Ingeniería Edificio O, Universidad Nacional Autónoma de México, Avenida Universidad 3000, Coyoacán, México D.F 04510, Mexico
Ortega I.:
Departamento de Materiales y Manufactura, Facultad de Ingeniería Edificio O, Universidad Nacional Autónoma de México, Avenida Universidad 3000, Coyoacán, México D.F 04510, Mexico
Jacobo V.H.:
Departamento de Materiales y Manufactura, Facultad de Ingeniería Edificio O, Universidad Nacional Autónoma de México, Avenida Universidad 3000, Coyoacán, México D.F 04510, Mexico
Ortiz A.:
Departamento de Materiales y Manufactura, Facultad de Ingeniería Edificio O, Universidad Nacional Autónoma de México, Avenida Universidad 3000, Coyoacán, México D.F 04510, Mexico
Bravo A.E.:
Departamento de Materiales y Manufactura, Facultad de Ingeniería Edificio O, Universidad Nacional Autónoma de México, Avenida Universidad 3000, Coyoacán, México D.F 04510, Mexico
Schouwenaars R.:
Departamento de Materiales y Manufactura, Facultad de Ingeniería Edificio O, Universidad Nacional Autónoma de México, Avenida Universidad 3000, Coyoacán, México D.F 04510, Mexico
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