Abstract
Oxygen diffusion from oxides to an alloy during heat treatment could influence the properties of the alloy and oxides. To clarify the influence of FeO on the solid-state reactions between Al2O3–CaO–FeO oxide and Fe–Al–Ca alloy during heat treatment at 1473 K, three diffusion couples with different FeO concentrations in the oxide were produced. The diffusion couples were subjected to several procedures successively including an oxide pre-melting experiment using a confocal scanning laser microscope to obtain good contact between the alloy and oxide, vacuum sealing to protect the specimens from oxidation, heat treatment, and electron probe X-ray microanalysis. The effects of the FeO content in the oxide on the morphology of the interface between the alloy and oxide, change of elements in the alloy, widths of the particle precipitation zone (PPZ) and aluminum-depleted zone (ADZ), and size distribution of the particles in the alloy, were investigated and discussed. Based on the Wagner equation of internal oxidation of metals, a modified dynamic model to calculate the PPZ width was established to help understand the mechanism of the solid-state reactions and element diffusion between the Fe–Al–Ca alloy and Al2O3–CaO–FeO oxide with different FeO concentrations.
Highlights
Accurate control of the physicochemical characteristics of non-metallic inclusions is beneficial to effectively improve the cleanliness of molten steel and quality of steel products [1,2]
According the observation by electron probe X–ray microanalysis (EPMA), in 1alland 2 in Figure 4a–c) precipitated in the alloy and a narrow precipitation zone (PPZ) was found near the alloy–oxide interface, in Figure precipitated in the alloy and a narrow was found near the alloy–oxide interface, cases, good contact was obtained between the alloy and oxide
Our results suggest that when the initial FeO content in the oxide was relatively high, such as that in diffusion reaction occurred between elemental
Summary
Accurate control of the physicochemical characteristics of non-metallic inclusions is beneficial to effectively improve the cleanliness of molten steel and quality of steel products [1,2]. With the development of the iron and steel industry, modern production processes for clean steel are becoming mature and standardized. Control and removal of non-metallic inclusions in steel require further improvement. Exploration of new processes to produce the steel with the desired cleanliness and quality currently attracts considerable attention [3,4]. Use of heat treatment processes to modify and optimize the physicochemical characteristics of non-metallic inclusions in steel is on the stage of continuous development [5,6,7]. Takahashi et al [8]
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