Most of the metal alloys are available in the MIM process. Typical alloy includes high strength steel, nickel and stainless steel and superalloy.
Other materials cover refractory alloy, titanium and copper alloy. Low melting point alloy refers to brass, bronze, aluminium and zinc, but these are not applicable to MIM metal injection molding process considering the cost.
If wanna know more, you can look over the table of material selections.