A double-cantilever beam crack growth sensor made from welded alloy, e.g., nickel-based alloy, and a method for fabricating such sensors. The method includes the steps of forming a strongback from a block of a first nickel-based alloy; depositing a suitable thickness of nickel-based weld alloy on top of the strongback to form a bi-metallic test block; welding a second block of the first nickel-based alloy on top of the weld alloy; and machining the final three-layer block to form a double-cantilever beam crack growth sensor consisting of cantilever beams made of the first nickel-based alloy, a crack growth section of weld alloy having a microstructure wherein the direction of dendritic growth is parallel to the direction of crack growth and a third section made of the first nickel-based alloy.