标题：Processing and characterization of an Al2O3/WC/TiC micro- nano-composite ceramic tool material
作者：Zhao, Jun; Yuan, Xunliang; Zhou, Yonghui
作者机构：[Zhao, Jun; Zhou, Yonghui] Shandong Univ, Key Lab High Efficiency & Clean Mech Mfg MOE, Sch Mech Engn, Jinan 250061, Peoples R China.; [Yuan, Xunlia 更多
通讯作者地址：[Zhao, J]Shandong Univ, Key Lab High Efficiency & Clean Mech Mfg MOE, Sch Mech Engn, 17923 Jingshi Rd, Jinan 250061, Peoples R China.
来源：MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
关键词：Micro- nano-composite ceramics; Mechanical properties; Microstructure;; Strengthening mechanisms; Toughening mechanisms
摘要：An Al2O3-based composite ceramic tool material reinforced with WC microparticles and TiC nanoparticles was fabricated by using hot-pressing technique with MgO and NiO as sintering aids. The experimental results showed that optimal mechanical properties were achieved for the composite with the addition of 24 vol.% TiC nano-particles and 16 vol.% WC microparticles, with the flexural strength, fracture toughness and Vicker's hardness being 842 MPa, 6.82 MPa m(1/2) and 22.19 GPa, respectively. The microstructure and phase composition of the composites were characterized with scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The fracture surface of the Al2O3/16 vol.%WC/24vol.%TiC micro- nano-composite was characterized by a mix of intergranular and transgranular fracture as a result of the presence of both intergranular and intragranular secondary phase particles. It is believed that inhibition of matrix grain growth by intergranular secondary phase particles, sub-grain boundaries and dislocations pinning inside Al2O3 grains induced by intragranular TiC nano-particles contribute to the strengthening of the composite. Meanwhile, the dislocations and microcracks inside the matrix grains can also increase the flaw-tolerance leading to high toughness of the composite. Additionally, some extrinsic processes including crack deflection, crack bridging and crack branching caused by the microstructural discontinuities and local stress state can absorb a great amount of fracture energy, which are beneficial for the toughening of the composite. However, future research will need to quantitatively understand the synergistic effect of TiC nano-particles and WC microparticles on strengthening and toughening mechanisms. (C) 2009 Elsevier B.V. All rights reserved.