Fracture energy and R-curve behavior of Al2O3/Mo composites

✍ Scribed by O. Sbaizero; G. Pezzotti; T. Nishida

• Publisher: Elsevier Science
• Year: 1998
• Tongue: English
• Weight: 411 KB
• Volume: 46
• Category: Article
• ISSN: 1359-6454
• DOI: 10.1016/s1359-6454(97)00292-9

✦ Synopsis

AbstractÐThe mechanical properties of a polycrystalline Al 2 O 3 containing increasing fractions of molybdenum particles are examined with particular emphasis placed on the fracture behavior. From the experimental side, both the fracture energy and the rising R-curve behaviour of the composites are measured as a function of the volume fraction of the metal dispersoid. A 20 vol.% fraction of metal dispersoid was found to markedly enhance the fracture energy of the Al 2 O 3 matrix as well as to make more pronounced its rising R-curve behavior. Microscopic observation of the crack path and fracture surface revealed the presence of stretched metal particles acting as ductile bridging sites behind the crack tip. Assuming crack bridging as the main mechanism contributing to toughening, a Dugdale-like theoretical model which considers the crack faces being shielded by a constant (average) closure stress ®eld is invoked to explain the fracture behavior of the composites.