This study is grounded in thermodynamic phase diagram calculations and employs powder metallurgy techniques to fabricate ultra-coarse grained WC-8(Co,Ni) cemented carbides with varying Ni:Co ratios. The study delves into the alloy"s microscopic structure, mechanical properties and corrosion resistance. It has been shown that carbon equilibrium can be efficiently maintained by using thermodynamic phase diagram calculations, thus preventing the emergence of harmful phases associated with carbon deficiency or excess in the alloy. As the Ni:Co ratio increases, the density of the alloy first increases and then decreases. The average grain size of WC enlarges, leading to a deterioration in the uniformity of the binder phase distribution. This results in a decrease in hardness, an increase in fracture toughness, and an initial rise followed by a significant decrease in flexural strength. Ni plays a crucial role in mitigating the corrosion rate of the binder phase and thus enhancing the corrosion resistance of ultra-coarse grained cemented carbides. When the Ni:Co ratio is 2:6, the alloy demonstrates optimal integrated mechanical properties and its enhanced corrosion resistance is notably pronounced.