J Mater sci(2007)42:763-771 Results between heating and cooling measurement runs. Te ssess material variability take Characterisation of as-received material on four samples cut from different regions of the as-received plate. The results are plotted in Fig. 2 and To identify the phases present in the as-received show a scatter of *3%. The median value obtained material, the X-ray diffraction studies were carried from this curve will be included, for comparison out on the samples. Figure 1 shows a typical scan over purposes in all future diffusivity/temperature plots the range 10< 20 <70 from which three crystalline Changes in thermal diffusivity were noted for the phases have been identified: Barium osumilite(BaMg2 samples heat treated for times as short as 1 h at Al3(SigAl3O30)), hexacelsian(BaAl3Si2Os)and cor- temperatures of 700 and 900C. However for higher dierite(Mg2AlgSis O1s) temperature anneals at 1,000-1, 200C, a negligible change was noted. The thermal diffusivity data after 1 h Thermal properties heat treatment in the range 700-1, 200C are presented in Fig 3. It can be seen that the greatest degradation Thermal diffusivity measurements thermal diffusivity is noted for the sample heat treated at700° C with the value of44×10-3cm2s-lwas Thermal diffusivity was measured over the tempera- measured at 100C and fair ture range 100-1,000C. There was no change noted 3.44 x 10 cm-s of being recorded above 350C. Fig. 2 Measurement of thermal diffusivity of BMAS/ a AR2 SiC as-received materials AR: Samples cut from different regions of the as- 0.007 0.006 0.005 010020030040050060070080090010001100 erc] Fig 3 Measurement of 0.008 thermal diffusivity of BMAS/ Sic after heat treatment for 900°c I h in air 0.007 0.005 0.003 010020030040050060070080090010001100 Temperature rclResults Characterisation of as-received material To identify the phases present in the as-received material, the X-ray diffraction studies were carried out on the samples. Figure 1 shows a typical scan over the range 10 < 2h < 70 from which three crystalline phases have been identified: Barium osumilite (BaMg2 Al3 (Si9Al3O30)), hexacelsian (BaAl3Si2O8) and cor￾dierite (Mg2Al4Si5O18). Thermal properties Thermal diffusivity measurements Thermal diffusivity was measured over the tempera￾ture range 100–1,000 C. There was no change noted between heating and cooling measurement runs. To assess material variability, measurements were taken on four samples cut from different regions of the as-received plate. The results are plotted in Fig. 2 and show a scatter of ±3%. The median value obtained from this curve will be included, for comparison purposes in all future diffusivity/temperature plots. Changes in thermal diffusivity were noted for the samples heat treated for times as short as 1 h at temperatures of 700 and 900 C. However for higher temperature anneals at 1,000–1,200 C, a negligible change was noted. The thermal diffusivity data after 1 h heat treatment in the range 700–1,200 C are presented in Fig. 3. It can be seen that the greatest degradation in thermal diffusivity is noted for the sample heat treated at 700 C with the value of 4.4 · 10–3 cm2 s –1 was measured at 100 C and fairly constant value 3.44 · 10–3 cm2 s –1 of being recorded above 350 C. Fig. 2 Measurement of thermal diffusivity of BMAS/ SiC as-received materials. AR: Samples cut from different regions of the as￾received composite Fig. 3 Measurement of thermal diffusivity of BMAS/ SiC after heat treatment for 1 h in air 123 766 J Mater Sci (2007) 42:763–771