TY - JOUR
T1 - Infiltration-processed, functionally graded aluminium titanate/zirconia-alumina composite
T2 - Part II Mechanical properties
AU - Pratapa, S.
AU - Low, I. M.
N1 - Funding Information:
S. Pratapa is very grateful to the Australian Agency for International Development for providing a scholarship. I. Low is grateful to the Australian Research Council and the Australian Institute of Nuclear Science and Engineering (AINSE) for financial support (AINSE Grant 96/142), and to Professor K. Niihara of Osaka University, Japan, and Dr B. Lawn of the National Institute of Standard and Technology, Maryland, USA, for providing facilities to perform measurements of Young’s modulus and Hertzian contact damage respectively. We thank Professor B. O’Connor and Ms E. Miller for proof reading and assistance with scanning electron microscopy, respectively.
PY - 1998
Y1 - 1998
N2 - The nature and degree of deformation-microfracture damage around Vickers indentations in a layered and graded aluminium titanate (AT)/(alumina-zirconia (AZ)) composite is studied. Samples with a homogeneous layer of AZ and a graded layer of heterogeneous AT/AZ are fabricated by an infiltration route. Depth profiling of the Vickers hardness shows that the hardness of the material is depth dependent with a relatively soft graded layer but a hard homogeneous layer. The microhardness of the graded layer is load dependent with 5.6 GPa as the asymptotic value at high loads. The evolution and accumulation of damage modes beneath Hertzian contacts are examined using "bonded-interface" sections. The stress strain response of the material is monitored by Hertzian tests. The graded layer exhibits a distinctive "softening" in the stress strain curve, indicating a microscale quasiplasticity which can be associated with grain debonding, grain sliding, diffuse microcracking, grain push-out and grain bridging. No contact-induced cracks are observed in the graded layer and the micro damage is widely distributed within the shear compression zone around and below the contacts. The capability of the graded material to absorb energy from the loading system and to distribute damage is somewhat akin to that of ceramics with heterogeneous microstructures.
AB - The nature and degree of deformation-microfracture damage around Vickers indentations in a layered and graded aluminium titanate (AT)/(alumina-zirconia (AZ)) composite is studied. Samples with a homogeneous layer of AZ and a graded layer of heterogeneous AT/AZ are fabricated by an infiltration route. Depth profiling of the Vickers hardness shows that the hardness of the material is depth dependent with a relatively soft graded layer but a hard homogeneous layer. The microhardness of the graded layer is load dependent with 5.6 GPa as the asymptotic value at high loads. The evolution and accumulation of damage modes beneath Hertzian contacts are examined using "bonded-interface" sections. The stress strain response of the material is monitored by Hertzian tests. The graded layer exhibits a distinctive "softening" in the stress strain curve, indicating a microscale quasiplasticity which can be associated with grain debonding, grain sliding, diffuse microcracking, grain push-out and grain bridging. No contact-induced cracks are observed in the graded layer and the micro damage is widely distributed within the shear compression zone around and below the contacts. The capability of the graded material to absorb energy from the loading system and to distribute damage is somewhat akin to that of ceramics with heterogeneous microstructures.
UR - http://www.scopus.com/inward/record.url?scp=0001269191&partnerID=8YFLogxK
U2 - 10.1023/A:1004375218439
DO - 10.1023/A:1004375218439
M3 - Article
AN - SCOPUS:0001269191
SN - 0022-2461
VL - 33
SP - 3047
EP - 3053
JO - Journal of Materials Science
JF - Journal of Materials Science
IS - 12
ER -