Microstructural characterization of Mg–Al–O rich nanophase strengthened Fe–Cr alloys

Publication date: Available online 11 November 2019Source: Materials Science and Engineering: AAuthor(s): Lei Dai, Zhong Liu, Liming Yu, Yongchang Liu, Zengmin ShiAbstractFe–9Cr ODS alloys elaborated by mechanical milling (MM) and followed by hot isostatic pressing (HIP) and hot rolling (HR) have been studied using transmission electron microscopy (TEM) and atom probe tomography (APT) to understand their microstructural characterization. The as-HIP alloy exhibited equiaxed ferrite and contained nanoparticles and low density of dislocations. The as-HR alloy manifested elongated ferrite and contained nanoclusters and high density of dislocations. Characteristics of Mg–Al–O rich nanophase may give insight into competitive behavior between nanofeatures’ constituents which involves nucleation of Mg–Al–O cluster as core at first and then segregation of W and Y at peripheral location. Fracture morphology of tensile test specimens at room temperature is also revealed by scanning electron microscope (SEM). That for the as-HIP alloy is a single ductile fracture (dimples), while the as-HR alloy exhibits a mixed mode of cleavage and ductile fracture characterized by steps, facets and limited ductile ridges (dimples). The SEM observations indicate that Mg–Al–O rich nanophase can serve as a source of dimples and cracks formation (in both alloys), and especially that significant impediment of crack propagation (only in the as-HR alloy) which result in deflection or terminati...
Source: Materials Science and Engineering: A - Category: Materials Science Source Type: research