Two-body abrasion of a cast Al-Cu (2014 Al) alloy-Al2O3 particle composite:: influence of heat treatment and abrasion test parameters

An Al-Cu (2014 Al) alloy reinforced with 10 vol. % Al2O3 particles (size: 75-150 mum), prepared by liquid metallurgy route, has been investigated under two-body (high stress) abrasive wear condition. The influence of varying load, abrasive size and sliding distance on the abrasive wear behaviour of the specimens was also studied. The base alloy prepared under similar condition has also been studied under identical test conditions in order to understand the influence of the dispersoid phase on the abrasive wear characteristics of the (base) alloy. In order to assess the role of matrix microstructure, the composite as well as the base alloy was subjected to abrasion in heat treated as well as in cast conditions. The results indicate that the Al2O3 particle reinforced cast Al alloy composite was more wear resistant (less wear rate) than the (unreinforced) matrix alloy when tested against 20, 35 and 60 mum size abrasive particles over the entire range of loads and sliding distances due to protection provided by the Al2O3 particles to the alloy matrix. On the other hand, a reverse trend was observed when 100 mum size abrasive particle was used as the abrasive medium above 1 N load due to greater microcracking tendency followed by fragmentation of dispersoid/abrasive particles. Unlike cast composite, heat treated composite exhibited better wear resistance (lesser wear rate) than the matrix alloy even when the tests were conducted against 100 mum size abrasive particles over the entire range of loads and sliding distances. Matrix strengthening and the morphological changes of the precipitate particles caused lower wear rate of the heat treated base alloy and composite over the cast ones. Abrasive wear rates were observed to decrease with sliding distance because of the increased extent of clogging, capping, shelling and attrition of the abrasive particles as well as subsurface hardening of the matrix. The wear behaviour of the specimens has been explained in terms of wear-induced subsurface work hardening, protection provided by the reinforced particles (in the case of composite) and degradation of the abrasive. Material removal mechanisms have also been studied through the examination of wear surfaces, subsurfaces, debris and abrasive particles. (C) 2001 Elsevier Science B.V. All rights reserved.