Ultrafinehigh-cobalt hard alloy VK40. II.Connection between mechanical properties and structure

Abstract

The experimental dependences of strength, plastic properties, hardness, and fracture etoughness on sintering or pressing temperature for ultrafine alloy WC-41 wt.% Co are presented. The alloy densifies in solid phase and temperature varies from 950 to 1250 "C. Thedependences of mechanical properties are extreme, excepting fracture toughness. The properties reach their maximum values at 1050 to 1150 ° С depending on the type of testing. Fracture toughness continuously increases with densification temperature. The highest values of some properties are reached after additional solid-phase annealing. The mechanical proper-ties of ultrafine high-cobalt alloy samples are assessed with the use of structural parameters and empirical equations established for standard hard WC-Co alloys sintered in liquidphase. The calculated and experimental values of properties differ: transverse rupturestrength, fracture toughness, and yield strength show higher values, while hardness and compressive strength have lower values as compared with calculated ones.