Wear and Corrosion Behavior of Spark Plasma Sintered Iron-Based Bulk Metallic Glass Composites and Coatings

Abstract

Bulk metallic glasses (BMGs) exhibit exceptional strength, hardness and wear and corrosion resistance due to their disordered atomic structure. Various Zr-, Ni-, Ti-, Cu- and Fe- based BMGs were processed using rapid solidification techniques. However, high cooling rates necessary in conventional solidification methods limit the critical diameter of the alloy to a few centimeters. Spark plasma sintering (SPS) provides an alternate solid-state processing approach without the need for high cooling rates because of mechanisms such as Joule heating, making use of pulsed direct current. This enables processing of fully dense BMG's. This technique has been extensively employed to process Cu-, Ti- and Zr-based metallic glasses, their composites, and coatings. In order to utilize the availability of inexpensive Fe-based metallic glasses with excellent mechanical properties, this thesis investigates the processing and evaluation of wear and corrosion resistant composites and coatings of Fe48Cr15Mo14Y2C15B6 metallic glass. Spark plasma sintered metallic glass composites exhibited anodic polarization in corrosive chloride environment and highest wear resistance with 5 vol.% Ni reinforcement. Coatings of this metallic glass on Cu-Ni alloy exhibited the lowest wear upon processing just below the crystallization temperature. Therefore, this study validates SPS as a promising solid-state processing route to manufacture Fe-based metallic glass composites and coatings