An environmentally resistant coating for improving the oxidation resistance of a niobium-based refractory metal intermetallic composite (Nb-based RMIC) at high temperatures, the environmentally resistant coating comprising silicon, titanium, chromium, and niobium. The invention includes a turbine system having turbine components comprising at least one Nb-based RMIC, the environmentally resistant coating disposed on a surface of the Nb-based RMIC, and a thermal barrier coating disposed on an outer surface of the environmentally resistant coating. Methods of making a turbine component having the environmentally resistant coating and coating a Nb-based RMIC substrate with the environmentally resistant coating are also disclosed.