Effect of hydrogen in rf plasma nitriding on Al-6wtCu alloy

摘要

In this work, plasma nitriding of Al-6wt%Cu alloy was carried out using radio frequency inductively coupled plasma (rf-ICP). The nitrided sample was performed under various percentages of hydrogen gas mixture (25%H_2+75%N_2, 50%H_2+50%N_2, 75%H_2+25%N_2, and 100%N_2) with the input rf power of 200 W and working pressure of 0.5 torr. The plasma nitriding process time was set at 6 h. The substrate temperature was kept between 290°C and 316°C. The AlN hexagonal (wurtzite) crystal structures were identified by X-ray Diffraction (XRD). Electron probe micro analysis (EPMA) was carried out in order to determine the nitrogen profile. Nitrogen content in all samples was obtained in this experiment. However, only 25%H_2 with 75% nitrogen, 50%H_2 with 50%N_2, and with 100% nitrogen was able to clearly indicate the crystal structure of AlN. The surface hardness was measured by using nanoindentation with a Berkovich indenter.