A heavyweight solution for lighter-weight combat vehicles. Researchers have developed and successfully tested a novel process -- called Friction Stir Dovetailing -- that joins thick plates of aluminum to steel. The new process will be used to make lighter-weight military vehicles that are more agile and fuel efficient. Source 9c.
They may be lighter but using aluminum will mean a higher cost specially for it to be hard enough to protect against incoming fire / missiles.
International Level: New Activist / Political Participation: 16 1.6%