Microstructural, tribological, and texture analysis of friction surfaced Al-Mg-Cu clad on AA1050 alloy

Abstract

In the present study, the effect of axial feeding rate of the consumable rod was investigated on the microstructure, texture, and tribological characteristics of AA2024 aluminum alloy cladding over AA1050 alloy. Optical metallography and scanning electron microscopy were used to characterize the microstructure of the coating. The texture of the coating was evaluated by macrotexture measurement using X-ray diffraction. The shear punch, microhardness, and dry sliding wear tests were performed to measure the mechanical properties, hardness, and wear characteristics of the coatings, respectively. The results showed that the high cooling rate at the substrate/coating interface resulted in small grain size in this zone, as well as a gradient structure of precipitates and grains form the top to the bottom of the coating. At a high axial feeding rate (200 mm/min), precipitate size and distribution were found to be the dominant factors in the strengthening of the coating. However, at a low axial feeding rate (75 mm/min), the grain size was introduced as the dominant factor in the enhancement of the coating strength and hardness. Furthermore, the results revealed that an increase in coating hardness was accompanied by a decrease in the friction coefficient. For coating with the highest hardness, the friction coefficient (0.45) approached its corresponding value in the consumable rod (0.42). Also, as the axial feeding rate increased, the recrystallization and shear texture in the coating were weakened. The texture weakening can be attributed to dynamic recrystallization, particle-stimulated nucleation, and Zener pinning.