PURPOSE: To prevent the occurrence of cracks in the surface of a sintered alloy in the sintering of Ti-base cermet by keeping a partial pressure of CO in a temp. raising stage to a sintering temp. to be held under a specified partial pressure of CO.
CONSTITUTION: Powder consisting of 70W97wt% hard compound phase composed of Ti as a principal component, a IVa, Va or VIa group metal and ≥1 kind of nonmetallic component selected from carbon, nitrogen and oxygen, and 3W30% binding phase of ≥1 kind of iron group metal is mixed and die-pressed. The die-pressed body is heated from ordinary temp. to 1,000°C in a vacuum, and a part or the whole of a temp. raising stage before attaining the sintering temp. is kept under 0.1W1 Torr partial pressure of CO. The die-pressed body is then held in a vacuum and sintered at the prescribed temp. By this method a sintered hard alloy (cermet) free from surface cracks for a tool, etc. is obtd.
IIDA TOSHIHIRO
DOI AKIRA
SAKAGAMI HITOSHI
YAMAKAWA AKIRA
