A nickel-based alloy composition is disclosed comprising from about 0.05 to about 3 percent by weight beryllium; from about 1 to about 40 percent by weight copper; no greater than about 10 percent by weight chromium, the balance being nickel. The alloy composition may be adjusted to achieve a high, as-cast hardness alloy over a wide range of alloy component contents, or a moderate, as-cast hardness alloy useful for forming articles such as golf clubs which has relatively constant mechanical properties over a wide range of copper contents.