Cemented carbide, cutting tool including same, and method of producing cemented carbide

A cemented carbide comprising:

• first hard phase grains each including WC;
• second hard phase grains each including a carbonitride containing Ti and Nb;
• and a metal binder phase including an iron group element, wherein
• each of the second hard phase grains includes a core portion in a form of a grain and a peripheral portion that coats at least a portion of the core portion,
• the core portion is composed of a composite carbonitride represented by Ti1-X-ZNbXMZC1-YNY,
• the M is at least one impurity element selected from a group consisting of V, Cr, and Mo,
• the X is more than or equal to 0.1 and less than or equal to 0.2,
• the Y is more than or equal to 0.3 and less than or equal to 0.6,
• the Z is more than or equal to 0 and less than or equal to 0.02,
• the peripheral portion has a composition different from a composition of the core portion, and
• a number of unit regions in which a percentage of the number of core portions in each of the unit regions with respect to the total number of core portions is less than 0.43% or more than 2.43% is less than or equal to 10, where
• the cemented carbide has a total of 70 unit regions,
• the total of 70 unit regions that are each constituted of a square having each side of 8 μm are provided by successively arranging 7 unit regions in a longitudinal direction and 10 unit regions in a lateral direction in an electron microscope image of any cross section of the cemented carbide captured at a magnification of 1500×, and
• the total number of core portions in the total of 70 unit regions is calculated by counting the number of core portions in each of the unit regions.