Sammendrag
A digital photocalorimetric technique has been developed and applied to obtain in situ temperature measurements from chill-block melt spun ribbons of a Mm(NiCoMnAl)5 hydride forming alloy. Compared with conventional colour transmission temperature measurements, this technique offers a special advantage in terms of a high resolution and positional accuracy, which under the prevailing experimental conditions are found to be ± 29 K and ± 0.1 mm, respectively. Moreover, it is shown that the cooling rate in the solid state is approximately 2.5 times higher than observed during solidification, indicating that the solid ribbon stays in intimate contact with the wheel surface down to very low metal temperatures before the bond is broken. During this contact period the cooling regime shifts from near ideal in the melt puddle to near Newtonian towards the end, where transfer from the solid ribbon to the wheel becomes the rate-controlling step.
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