Is there any way to combine multiple alloys, in this case titanium alloys, into one composition for, in this case, protective outer shells for military use in the future.

These are the alloys:

• Alloys Ti-5Al-2Sn-2Zr-4Mo-4Cr (commonly called Ti-17) and Ti-6Al-2Sn-4Zr-6Mo for high strength in heavy sections at elevated temperatures.
• Alloys Ti-6242S, IMI 829, and Ti-6242 (Ti-6Al-2Sn-4Zr-2Mo) for creep resistance
• Alloys Ti-6Al-2Nb-ITa-Imo and Ti-6Al-4V-ELI are designed both to resist stress corrosion in aqueous salt solutions and for high fracture toughness
• Alloy Ti-5Al-2,5Sn is designed for weldability, and the ELI grade is used extensively for cryogenic applications
• Alloys Ti-6Al-6V-2Sn, Ti-6Al-4V and Ti-10V-2Fe-3Al for high strength at low-to-moderate temperatures

Alloys are pretty specific and for a purpose. People use the term Stainless Steel but there are about 50 alloys, all designed with a specific goal in mind. For example, if you use 400 series stainless where 300 series is needed, you will have serious corrosion issues. Because of the cost of some of the alloys, they will use a laminate or composition mat rather than a specific alloy. Use a thin high strength alloy over an Aluminum Composite as an example.

If you are asking about creating a laminate of several different alloy sheets to create a strong shell - I do believe that's possible, though binding the layers may require special processes. But if you are asking whether combining alloys in molten form prior would create a new alloy with the superior properties of each of the constituent alloys - no. Material scientists spend their careers trying to develop alloys with superior properties, and simply combining one alloy with another will not yield a new alloy with combined properties of both.

That's a very expensive way to cover something designed to blow up. Not practical since there are cheaper alternatives, but you never know.

Just thought you may want to add more to specifics of metallurgy, have you heard of Superalloys? They are generally polymer metal composites with semicrystalline structures.