I am also curious to know which company is supplying such bulk aluminum matrix composites (AMCs). Duraclan (a division of Alcan Aluminum Ltd.) is known to supply AMCs. Please check the following link.
http://www.temponik.com/Duralcan%C2%AE-2
We have also produced AA7075/TiB2 AMCs in our lab successfully. Please check our following publications.
Article Synthesis and characterization of in situ formed titanium di...
Article Influence of friction stir processing on microstructure and ...
Article Turning characteristics of in situ formed TiB2 ceramic part...
However, we do not have facility in our lab to produce such huge plates. If a facility can be funded, we can produce at Center for Research in Metallurgy located in Karunya University, INDIA .