FRACTURE TESTING AND ATOMISTIC MODELING TECHNIQUES FOR FRACTURE OF PARTICLE REINFORCED COMPOSITES HARDMETALS

Open Access
Author:
Byrne, Erik
Graduate Program:
Engineering Mechanics
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
November 12, 2008
Committee Members:
  • Ivica Smid, Thesis Advisor
Keywords:
  • fracture toughness testing
  • particle reinforced composite hardmetals
Abstract:
Manufacturing companies that process difficult-to-machine materials rely on dependable cutting tools that have long service lifetimes. Tough coated hard particle (TCHP) based hardmetals are novel materials that make exceptional cutting tools. TCHP is a hard particle reinforced composite hardmetal that has many advantages over the WC-Co cutting tools that have been favored by industry for over 80 years. Microstructural evaluations of press and sinter and hot-pressed TCHP parts show that either technique is capable of producing dense, high quality, and defect free parts. Understanding TCHP’s composite microstructure helps in understanding the effects its microstructure has on fracture. Instrumented impact testing was used to show that TCHP hardmetals have an impact toughness which exceeds that of WC-Co of equal cobalt content by 26% due to complex crack interactions with the microstructure. The fracture toughening mechanism of crack deflection around core particles gives TCHP composites additional toughness. Using a molecular dynamics simulation to model crack interactions with TCHP’s microstructure at the atomic scale is a necessary step in quantifying the effect that crack deflection around core particles has on TCHP’s toughness.