Bryan,
My father told me about an interesting welding technology when two metals are joined together in a vacuum chamber by heating the joining points with a laser, that creates a diffusion effect that joins the parts together. He was on a demonstration of such a device in Russia some years ago. He said, that in this way you can join together many different metals, he said that he was shown a piece of glass joined together with a piece of wood The join line was semitransparent like you had melted together transparent plastic with white plastic
Unfortunately I do not know anything else about this technology