Cobalt-based alloy compositions are described herein having properties compatible with thermal spray and sintering techniques. Such alloy compositions can provide claddings to a variety of metallic substrates having complex geometries, wherein the claddings exhibit desirable density, hardness, wear resistance and corrosion resistance. Briefly, an alloy composition described herein comprises 15-25 wt. % chromium, 15-20 wt. % molybdenum, 0-15 wt. % tungsten, 10-20 wt. % nickel, 2.5-3.5 wt. % boron, 2.5-4.5 wt. % silicon, 1-2 wt. % carbon and the balance cobalt, wherein a ratio of boron to silicon (B/Si) in the alloy composition ranges from 0.5 to 1.0.