A composition of matter, comprising in combination, in atomic percent contents: a content of nickel as a largest content; 19.0-21.0 percent cobalt; 9.0-13.0 percent chromium; 1.0-3.0 percent tantalum; 0.9-1.5 percent tungsten; 7.0-9.5 percent aluminum; 0.10-0.25 percent boron; 0.09-0.20 percent carbon; 1.5-2.0 percent molybdenum; 1.1-1.5 percent niobium; 3.0-3.6 percent titanium; and 0.02-0.09 percent zirconium.