Processing, As-Cast Microstructure and Wear Characteristics of a Monotectic Al-Bi-Cu Alloy
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Ternary Al-based monotectic alloys have a good combination of wear resistance and mechanical strength. While self-lubricating soft elements guarantee an adequate wear resistance, the modification with third elements can increase the ability to support load. In the present investigation, a collection of microstructures is generated through transient directional solidification of the Al-3.2wt.%Bi-3.0wt.%Cu alloy. Samples with different Bi spacing have been subjected to micro-adhesive wear ball tests. A relationship linking the wear volume, V, the microstructural spacing and the test time is proposed for Bi spacing higher than 16 μm, according to which V decreases with the decrease in Bi spacing. It is observed that wider and deeper grooves emerged on the surface of the samples related to more refined Bi and Al2Cu phases, that is, associated with Bi spacing and Bi diameter lower than 16 and 2.4 μm, respectively. A reverse trend is noted for these finer microstructures, for which V increases with further decrease in Bi spacing. This can be caused by the detachment of the very fine and less cohesive Al2Cu lamellas as the Al2O3 oxide breaks up forming debris, with the presence of these lamellas as loose debris at the interface acting as third-body abrasives.
KeywordsAl alloys microstructure monotectics solidification wear
The authors are grateful to FAPESP (São Paulo Research Foundation, Brazil: Grant 2017/12741-6) and CNPq- National Council for Scientific and Technological Development, for their financial support.
Conflict of interest
The authors of this manuscript declare that they have no conflict of interest.
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