Formation of a wear-induced layer with nanocrystalline structure in Al–Al3Ti functionally graded material

A new severe plastic deformation (SPD) process to obtain nanocrystalline (NC) structure by wear is reported. An Al–Al3Ti functionally graded material fabricated by a centrifugal method is wear tested to investigate the microstructure of the wear-induced layer. When the sliding distance of the wear exceeds l = 100 m, the wear-induced layer is obtained just below the worn surface. The microstructure of the wear-induced layer consists of fine Al3Ti fibrous particles and an NC solid-solution matrix containing a partly amorphized phase. The NC matrix has fine grains with a mean diameter of 16 nm and is a supersaturated solid-solution in which Ti is dissolved in the Al matrix. From the microstructure, it is estimated that the wear-induced layer is formed at a nominal shear strain of more than 90 and an effective shear strain of more than 52. An NC structured wear-induced layer is generated by the SPD process.