Fig. 7. Microstructure of samples at sensor #2 position (Fig. 2). (a) and (b) casting temperature of 650 °C, for curves (2) and (1) respectively; (c) and (d) casting temperature of 700 °C, forpressure curves (2) and (1) respectively; (e) and (f) non-US degassed samples for casting temperature of 650 and 700 °C, for curve (1) respectively.