Yeah, I've got a magnesium alloy receiver myself. But I'm pretty sure it was cast, and I don't know that most knife or sword makers would have access to the kind of machinery and tools that it would probably take to machine magnesium alloy, let alone temper it. The receiver that I have is pretty easily scratched. It would be awful in a sword in it's current state. I'd wager it would take some specialized equipment and know-how to work with magnesium for a sword, and I don't think there's that many people that know how to temper magnesium alloy appropriately for a sword.
Castings really
have to be machined, to be usable for stuff like that. Holes, channels, etc., can't possibly meet the tolerances necessary, unless you're using one of those new amorphous alloys.
Anyway, though, the subject of the thread was if a titanium sword has any advantages over a steel one, so I've been thinking functional advantages rather than manufacturing ones. I guess titanium is more easily cast than steel. But anyway, the vast majority of sword makers would
also be a combination of clueless and frustrated with titanium, considering that the alloys hard enough to realistically make a blade are around 35 to 38
Rockwell C hardness when
dead-soft annealed, and require cryo age-hardening (I think for 3-6 months?) to reach their full hardness of 42 to 45-ish. About as strong as 4140, dimensionally, at the same hardness, though. Great for lightweight gun parts, but not much of a sword. And you obviously need a CNC machine and a truckload of bits.
Titanium's a real bear.
I'm also not sure if the aluminum or magnesium parts would even need to be tempered, for the kinda design I was talking about. Steel cutting edge laminated with something light, with the steel providing more than half of the rigidity and all of the edge, with the lightweight bits just making it a little stiffer and changing the overall edge geometry for better cutting performance (like machetes are too thin to split wood well, without batoning).
Like I said in my first post on this thread, not practical for much. I can't think of a thing. A sword or axe would end up too light. A scythe doesn't need edge geometry all the way to the spine, I don't think. Machetes are generally supposed to be so cheap they're semi-disposable, like a giant X-acto.
Only thing I can possibly think of for a laminated sword in general would be laminating
wood onto steel, in the event of an extreme metal shortage. Now I'm picturing what I'm going to call the Redneck Buster Sword. Take a very large large woodcutting saw, rig up a sword grip for it, sharpen and contour the back edge (so it's a sawback sword!), split a 2x4 lengthwise and broadwise, laminate that to the saw using rivets and JB weld, keeping it at least 1.5" or 2" or so back from the cutting edge, then contour and thin the wood bits so they still keep it stiff, but any added resistance is minimal, when cutting a soft target. And then JB weld it to the wall for display, so no one mutilates themselves with the sawback while trying to carve up a tree.
Well... maybe I should call it a Redneck Buster Sword if you remove the sawteeth, and an IRA (the Irish one) Buster Sword if you leave them on!