Mechanical behaviour of zirconia-mullite directionally solidified eutectics
authors Carvalho, RG; Oliveira, FJ; Silva, RF; Costa, FM
nationality International
journal MATERIALS & DESIGN
author keywords Directional solidification; Fibres; Mechanical properties; Mullite; Zirconia
keywords CERAMIC COMPOSITES; MICROSTRUCTURE; FIBERS; SYSTEM; TEMPERATURE; WHISKER; SINGLE; ALLOY
abstract Laser floating zone technique (LFZ) is used to grow directionally solidified eutectic (DSE) zirconia-mullite composite fibres (30:70 in wt.%). A notable increase in hardness is observed from 11.3 to 21.2 GPa as the pulling rate increases from 10 to 500 mm/h, due to the ultra-fine eutectics developed at very high growth rates. The indentation fracture toughness reaches a maximum value of 3.5 MPa m(1/2) for the fibre pulled at 100 mm/h, almost three times the value of 1.2 MPa m(1/2) determined for LFZ single-crystal mullite. The eutectic dendrites that develop along the growth direction are immersed in a glassy phase whose brittleness is counteracted by the beneficial ultra-fine morphology, giving a bending strength maximum of 534 MPa. Yet, the soft nature of the glassy matrix prevails at the high temperature testing (1400 degrees C), causing a decrease to about one-half of the RT value in the fibres with less glassy phase content. (C) 2014 Elsevier Ltd. All rights reserved.
publisher ELSEVIER SCI LTD
issn 0261-3069
year published 2014
volume 61
beginning page 211
ending page 216
digital object identifier (doi) 10.1016/j.matdes.2014.04.050
web of science category Materials Science, Multidisciplinary
subject category Materials Science
unique article identifier WOS:000337854100027
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