Mechanical properties of alumina–zirconia–Nb micro–nano-hybrid composites

Abstract

The multi-scale and multi-phase hybrid composite ceramic-metal materials Al 2 O 3 -nZrO 2 -Nb are successfully fabricated. Their mechanical properties are better compared to the single-phase alumina materials and conventional alumina-Nb composite materials. The coexist function of nano-scale ZrO 2 , which can increase the initial toughness and strength, and the micrometer lamellar Nb particles which increase the toughness, flaw tolerance and crack growth resistance, improve notably the mechanical properties of these hybrid composites. The mechanisms of toughening and strengthening were analyzed, and it was found that residual stress, generated by the different thermal coefficients between the Al 2 O 3 matrix and the ZrO 2 nanoparticles, and bridging of the Nb inclusions were the two main factors that can increase the initial level of the driving force for critical microcrack extension, and shield an advancing crack and exert crack closure stresses on the crack wake. The aim of this work is to develop mechanisms at a multiple of length scales in order to create a new hybrid material with unique mechanical properties.

In situ alumina/aluminum titanate bulk ceramic composites prepared by SPS from different structured composite powders

“…And several investigations showed that a smaller grain size (grain refinement) in alumina ceramics led to improved mechanical properties [5,[18][19][20][21][22]. The mechanical strength of Al 2 TiO 5 ceramics also increased as the grain size decreased [23].…”

“…However, the relatively high sintering temperature and low fracture toughness have limited its applications to some extent. It has been proved that incorporating suitable second phases into alumina is an effective way to lower its sintering temperature, control its microstructure and therefore improve its mechanical properties [1][2][3][4][5][6].…”

Mechanical and tribological properties of ceramic/metal composites: A review of phenomena spanning from the nanometer to the micrometer length scale

“…14), that open the possibility to tailor new materials with toughening mechanisms operating at different scales. 80 For a scale below the one of the matrix microstructure, this enhances the "intrinsic" fracture properties of the material. This intrinsic increase of resistance to crack initiation and propagation should lead to an increase in the catastrophic failure strength.…”

Residual strength of metal particulate reinforced ceramics with parallel cracks

“…A major toughening mechanism in metal particulate reinforced ceramics is crack surface bridging by the plastically stretched ductile particulates [3][4][5]. Extensive efforts have been made to understand toughening and the crack growth resistance behavior of the composites since 1980s [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25].…”