Superior wear resistance in cast aluminum alloy via femtosecond laser induced periodic surface structures and surface hardening layer

Cast Al alloys have been increasingly used in aviation, shipping, aerospace, and automotive industries as important raw materials of engine parts. However, its poor wear resistance hampered their application in some tribological environments. To overcome the current issue, in present work, we proposed a femtosecond laser (fs-laser) surface processing strategy to fabricate pillar-shaped laser induced periodic surface structures (LIPSS), as well as a work-hardening layer (hardness increment reached 51.2% compared with that of substrate) with an affected depth of ∼ 75 μm, on the surface of cast Al alloy in one step. In this case, the wear performance of processed samples showed an obvious improvement with a 49.4% reduction of the cross sectional area of wear track. Our work broke the existing understanding about the strengthening mechanism of fs-laser surface modification technology, in which surface texture or shock wave induced by fs-laser were viewed as two isolated strengthening effects. For the first time, we achieved the combination of these two strengthening effects, and proved the effectiveness of this strategy. The present results provided theoretical bases for the further development of novel fs-laser surface technologies with better performance.