Cemented carbide
A cemented carbide includes a tungsten carbide grain and a binder phase, wherein the cemented carbide includes 80 volume % or more of the tungsten carbide grain and the binder phase in total, the cemented carbide includes 0.1 volume % or more and 20 volume % or less of the binder phase, the tungsten carbide grain is composed of a first region and a second region, each of the first region and the second region includes a first metal element, the first metal element is at least one selected from a group consisting of titanium, niobium, and tantalum, a ratio R1 is 0.70 time or more and less than 1.30 times as large as a ratio R2, the R2 is 2.0% or more and 10.0% or less, and the binder phase includes cobalt.
1 . A cemented carbide comprising a tungsten carbide grain and a binder phase, wherein
the cemented carbide includes 80 volume % or more of the tungsten carbide grain and the binder phase in total,
the cemented carbide includes 0.1 volume % or more and 20 volume % or less of the binder phase,
the tungsten carbide grain is composed of a first region and a second region,
the first region is a region of 0 nm or more and 50 nm or less from a surface of the tungsten carbide grain,
the second region is a portion of the tungsten carbide grain other than the first region,
each of the first region and the second region includes a first metal element,
the first metal element is at least one selected from a group consisting of titanium, niobium, and tantalum,
a ratio R1 of the number of atoms of the first metal element to a total of the number of atoms of the first metal element and the number of atoms of a tungsten element in the first region is 0.70 time or more and less than 1.30 times as large as a ratio R2 of the number of atoms of the first metal element to a total of the number of atoms of the first metal element and the number of atoms of the tungsten element in the second region,
the R2 is 2.0% or more and 10.0% or less, and
the binder phase includes cobalt.
2 . The cemented carbide according to claim 1 , wherein the R1 is 0.75 time or more and 1.25 times or less as large as the R2.
3 . The cemented carbide according to claim 1 , wherein the R2 is 3.0% or more and 8.0% or less.
4 . The cemented carbide according to claim 1 , wherein the R1 is 2.6% or more and 12% or less.
5 . The cemented carbide according to claim 1 , wherein a content ratio of vanadium in the cemented carbide based on the number of atoms is 1.0 atm % or less.
6 . The cemented carbide according to claim 1 , wherein the R1 is 2.8% or more and 11.8% or less.
7 . The cemented carbide according to claim 1 , wherein a content ratio of vanadium in the cemented carbide based on the number of atoms is 0.8 atm % or less.
8 . The cemented carbide according to claim 1 , wherein the R1 is 0.8 time or more and 1.2 times or less as large as the R2.
9 . The cemented carbide according to claim 1 , wherein an average grain size of the tungsten carbide grains is 0.1 μm or more and 3.5 μm or less.
10 . The cemented carbide according to claim 1 , wherein an elastic modulus of the tungsten carbide grain is 450 GPa or more and 465 GPa or less.
11 . The cemented carbide according to claim 1 , wherein the content ratio of cobalt of the binder phase is 90 mass % or more and 100 mass % or less.