A metallic glass particle layer is applied to aluminum alloy armor and friction stir mixed into the surface in order to embed the material into the armor and to take advantage of its exceptional hardness. An advantage of the invention is that the hard material is an integral part of the armor, included within the body of the armor plate and not merely a surface coating. The advantage of the friction stir process is that it generates relatively low levels of heat and magnetic measurements show that the amorphous phase condition of the metallic glass is not deteriorated. The armor may be tempered to improve properties.