Microstructures of tribologically modified surface layers in two-phase alloys

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...

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Bibliographic Details
Published inIOP conference series. Materials Science and Engineering Vol. 63; no. 1; p. 12018
Main Authors Figueroa, C G, Ortega, I, Jacobo, V H, Ortiz, A, Bravo, A E, Schouwenaars, R
Format Journal Article
LanguageEnglish
Published Bristol IOP Publishing 08.08.2014
Subjects
Aluminum base alloys
Brittleness
Copper
Copper base alloys
Deformation wear
Eutectics
Flow distribution
Frictional wear
Magnesium
Mechanical alloying
Plastic deformation
Shear deformation
Sliding contact
Sliding friction
Strain
Surface layers
Tin
Tribology
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Summary: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 a- dendrites with a eutectic consisting of a brittle Cu2Mg-matrix with α-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 a 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.
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ISSN:1757-8981
1757-899X
DOI:10.1088/1757-899X/63/1/012018