Whats an unmeltable, strong, and decently light metal?
Everything is a compromise. You need to specify how strong, how light and how hot it needs to get. but having said that, Titanium and its alloys are worth looking at. Titanium has the highest strength to weight ratio of any metal and melts at 1649C (Aluminium melts at 933C). It is 60% heavier than Aluminium, but over twice as strong. It is highly corrosion resistant. The only reason it is not used more is because of its cost. P.S. If cost is no object, there is a material which is stronger and lighter than Titanium and which will not melt at any temperature. (if you can get it hot enough, it sublimes directly into vapour). Disadvantage is that it burns in air, is extremely difficult to work, and is not a metal: Diamond. PPS, a more practical suggestion would be ceramics. The properties you need are matched by the requirements for gas turbine blades. Ceramic or ceramic metal hybrids (cermets) are sometimes used for these.
