Deposition of amorphous layers of an FeBSi alloy by low pressure plasma spraying

Abstract

Powder of the alloy Fe15.2at.%B10.6at.%Si with high glass formability was plasma sprayed onto water-cooled steel and copper substrates in a low pressure chamber. Once formed on the steel substrate, the thin amorphous layer partly crystallized owing to the rise in temperature during spraying, whereas the layer on the copper substrate, 1.5 mm thick, remained amorphous. The maximum temperature that the layer on the copper substrate reached during spraying was estimated to be below 639 K. The amorphous deposited layer showed a differential scanning calorimetry exothermic reaction peak at 843 K when heated at a rate of 0.16 K s −1; cubic Fe 3Si, tetragonal Fe 2B, metastable tetragonal Fe 3B and ferrite were detected in the quenched layer. Crystallization occurred preferentially from the boundaries between the flattened particles composing the layer.