you do need to change radically the composition of an alloy to change radically its stiffness (elastic modulus)
anyone who can do this another way should first patent his method and then make billions
so we might have scope for 47 or 48% of tungsten in an alloy making the main part (crankshaft) ie that doing the hard work
the rules envisage THAs being used as bolt-on counterbalance weights
maybe a multi-piece crankshaft could be made from a THA and be legal unless protested
THAs or alloys with 48% tungsten could like Lockalloy (beryllium/aluminium 'alloys') be categorised as composites not alloys ?
tungsten will not form (solid) solutions with other constituents ?
hysteresis would be far higher ?? than our usual materials and cause significant self-heating (and, usefully, self-damping)