Formations of hard AZ31/TiN nano-composite surface layer employing friction stir processing technique |
Paper ID : 1392-UFGNSM-FULL |
Authors: |
Abstract: |
Friction stir processing was employed for surface modification of AZ31 magnesium alloy. AZ31/TiN composite surface layers were formed by introduction of nano-sized TiN powder into the stir zone of AZ31 magnesium substrates. A H13 steel tool with triangular pin was rotated and advanced on AZ31 substrate to plasticize a surface layer which mixed with the introduced TiN particulates. The effect of advancing speed was investigated on TiN dispersion within the fabricated composite surface layer. Microstructural observation using scanning electron microscopy showed that dispersion of TiN particulates was affected by friction stir processing parameters such as tool rotation & substrate advancing speeds and number of friction stir processing passes. A nano-composite surface layer with a uniform dispersion of nano-sized TiN particulates was achieved after four FSP passes using a tool rotation and substrate advancing speed of 1800 rpm and 50 mm/min, respectively. In addition, TiN dispersion was found to be effective on matrix grain refinement; the fabricated surface layer showed ultra fine grains with a mean matrix grain size of less than 1μm. The nano-composite surface layer exhibited a maximum value of hardness nearly two times of that of its underlying substrate using a Vickers indenter. |
Keywords: |
Friction stir processing, AZ31, TiN particles, nano-composite |
Status : Paper Accepted (Poster Presentation) |