Microstructure and tribological behavior of spark plasma sintered iron-based amorphous coatings

Spark plasma sintering (SPS) has been used to produce thick (∼400 μm) amorphous coatings of Fe48Cr15Mo14Y2C15B6 alloy composition on aluminum substrates. The coatings were fabricated using uniaxial pressure of 50 MPa over a range of temperatures (550–590 °C) below crystallization temperature (∼631 °C) of this glassy alloy. Under the investigated SPS processing parameters, the infiltration of the aluminum substrate material in the overlaid amorphous powder was observed resulting in composite amorphous coating. Detailed investigations on evolution of phases, microstructure, and interface characteristics in the amorphous coatings are presented. The amorphous coatings exhibited high surface hardness (∼880–1007 HV) and superior wear resistance (∼75–80% decrease in weight loss) compared to substrate material. The wear mechanisms were dominated by ploughing of soft aluminum phase in the interparticle regions, dislodging of amorphous particles, and microcutting (abrasion) of amorphous regions of the coatings.