Sliding wear behaviour of two gamma-based titanium aluminides

Lamellar Ti-48Al-2Nb-2Mn (at.%) and Ti-45Al-2Nb-2Mn-1B (at.%) titanium alum inides have been wear tested using a ball-on-disc configuration against a 1 0-mm-diameter hard steel ball under dry sliding conditions at applied loads of 3.5, 5, 10 and 20 N. The worn surfaces have bt:en characterised using o ptical microscopy, scanning electron microscopy, energy dispersive X-ray sp ectroscopy and microhardness measurements. Plastic deformation and ploughin g have been observed on the worn surfaces. The stresses imposed by friction near the surface caused a slight deformation of lamellae followed by inter lamellar boundaries slip resulting in the inter-lamellar cleavage and subse quently their fracture. Micro-fracture from the inter-lamellar cracks resul ted in the separation of fine-grained and flake-like debris. (C) 2000 Elsev ier Science S.A. All rights reserved.