METAL MATRIX COMPOSITES REINFORCED WITH INTERMETALLIC RIBBONS

The design procedure for low melting point alloy composites reinforced with melt-spun intermetallic ribbons for elevated temperature applications is presented. Long-range ordered Ni₃Al intermetallic is selected as a candidate reinforcement by virtue of its ease of being ductilized by boron and an increase in yield strength with increasing temperature. A certain composition of Ni₃Al alloyed with cobalt, tantalum, hafnium and boron for the maximum reinforcing effect is formulated. The rule of mixtures calculations of elastic modulus and yield strength are performed for Al-Si and Mg-Al matrices. The results of the structural investigation of a model composite system consisting of a 1100 Al matrix with embedded Ni₇₅Al₂₃Zr₁B₁ (at.%) ribbons, obtained by casting, are presented. Long-term stability of the reinforcing ribbons is investigated by annealing of “as-cast” specimens at elevated temperatures up to 100 h.