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Eutectoid decomposition of aluminum titanate (Al < inf > 2 < /inf > TiO < inf > 5 < /inf > ) ceramics under Spark Plasma (SPS) and Conventional (CRH) thermal treatments

( 2014-01-01) Papitha, R. ; Suresh, M. Buchi ; Chakravarty, D. ; Swarnakar, A. ; Das, Dibakar ; Johnson, Roy

Eutectoid decomposition of Al2TiO5, is a strong function of heating rate, exposure temperature and dopant chemistry. Al 2TiO5 specimens formed from the mixture of precursor oxides were subjected to Spark Plasma (SPS) and Conventional Ramp and Hold (CRH) heating to evaluate the extent of decomposition. SPS with heating rates of 200 C/min and 50 C/min under 50 MPa have shown phase decomposition of 95% and 74%, respectively. CRH conditions have resulted only in low phase decomposition of 11% however, substantial decomposition of 54% is observed on thermal cycling. A major slope change in dilatometric curve along with appearance of a new XRD peak at 40 in similar temperature regimes close to 1000 C complements initiation of decomposition. A significant retardation in eutectoid decomposition of Al 2TiO5 phase could be achieved by doping with 5 wt% of magnesium silicate as revealed by studies under identical conditions including SPS. Thermo-mechanical properties also correlated well with the observed decomposition profiles. © 2013 Elsevier Ltd and Techna Group S.r.l. All rights reserved.