Surface Alloying of Aluminum Alloy using Fe Powder by Laser Alloying Process

Laser alloying process has been investigated to make a thick hardened alloyed layer on the surface of commercial aluminum alloy (A5052) plate using the powder mixtures of Al with 20, 50, 70 and 100 mass% Fe. The measured hardeness and wear resistance of alloyed layer have been discussed in relation to the microstructure of alloyed layer. The optimum traveling speed to obtain a smooth surface decreases with the increase in Fe content in the powder mixture. There were four types of the microstructural morphologies in alloyed layer depending on Fe content in the powder mixture and traveling speed, namely cellular dendrite, needle-like FeAl3, fine needle-like FeAl3 and lump-like Fe2Al5. The hardness of alloyed layer with needle-like FeAl3, fine needle-like FeAl3 and lump-like Fe2Al5 were HV100-200, HV300-500 and HV700-900, respectively, though cracking occurred in the case of lump-like Fe2Al5 structure. The wear resistance of alloyed layer increased with the increase in hardness. The most desirable structure of alloyed layer for wear resistance was that with fine needle-like FeAl3 having 29-34 mass% Fe.