Improvement of Erosion Resistance of Aluminum- Copper Alloy Type 2024 by Plasma Nitriding

Abstract

 Samples from the aluminum-copper alloy 2024 were prepared to study the improvement of the erosion resistance of this alloy.  A full thermal annealing treatment was performed.  Plasma nitriding was performed as a surface treatment.  Microstructure examinations (SEM, XRD), erosion, and hardness tests were carried out after each treatment, and comparing the results.To increase the erosion resistance of 2024 Al alloys, plasma nitriding surface treatment was used. Nitrogen and argon gases are injected into an evacuated chamber until the pressure reaches 15 Pa. The process requirements for normal plasma nitriding were heating at 440˚C for 8 hours, low voltage of 650 V, current of 25 mA, low gas consumption, and no air pollution. A continuous nitriding layer of AlN was formed. The microhardness reached a maximum value of 170 HV, about 3 times higher than that Al melts at, is transported upward through voids and capillaries in the AlN structures, and reacted with N plasma in the melt surface. The growth of the AlN structures promotes this transport of un-nitride alloy subjected to the same heat treatments. As a result, the erosion rate of the nitrided samples decreased by 10% when compared to the ones that are not nitrided.