Characterization of Fe-based amorphous powder synthesized via mechanical alloying and consecutive consolidation via spark plasma sintering

Abstract

This thesis presents a comprehensive study on the synthesis, consolidation, and characterization of Fe-based amorphous alloy powders developed through MA and subsequently consolidated using SPS. Two ternary compositions Fe83.453Al14.560Ti1.987 and Fe69.815Al26.860Ti3.325 were selected based on their potential glass-forming ability and phase stability. The MA process, carried out for up to 80 hours, led to significant structural refinement and partial amorphization, as confirmed by X-ray diffraction (XRD), transmission electron microscopy (TEM), and selected area electron diffraction (SAED). Scanning electron microscopy (SEM) coupled with energy-dispersive X-ray spectroscopy (EDS) showed morphological evolution and compositional homogeneity with increased milling duration. Particle size analysis indicated a trend of particle refinement followed by agglomeration due to cold welding. Differential scanning calorimetry (DSC) highlighted distinct thermal transformation behaviors for both compositions. Subsequent SPS consolidation at temperatures ranging from 300 °C to 1200 °C resulted in improved densification, with Fe83.453Al14.560Ti1.987 exhibiting higher practical density and lower porosity. The XRD patterns of sintered samples revealed the formation of intermetallic phases at elevated temperatures, while SEM analysis demonstrated enhanced inter-particle bonding. Mechanical characterization using the Vickers hardness test showed a substantial increase in hardness with sintering temperature, with a maximum value of 1029 ± 8.7 HV for the Fe83.453Al14.560Ti1.987 sample sintered at 1200 °C. The results establish the effectiveness of combining MA and SPS to fabricate high-density Fe-based amorphous alloys with promising structural and functional properties.