Evolution of Microstructure Near Crack Tips in High-Strength Aluminum Alloy AA7075-T6 Sheet at 200 °C
摘要
The microstructureMicrostructure of AA7075-T6 sheet was characterized in the as-received condition and near the crack tip of material subjected to ductile tearingTearing at 200 °C. Different characterizationCharacterization techniques were used, including optical microscopy (OM), scanning electron microscopyElectron microscopy (SEM), and x-ray computed tomographyX-Ray Computed Tomography (XRCT). Each technique revealed anisometry of microstructural features, with features generally aligned with the sheet rolling direction. Cavities and multiple classes of large constituent second-phase particles were segmented in fields of data from the as-received material using a correlative microscopyCorrelative microscopy (CM) technique. From CM data, two-point correlations were calculated between constituent particle classes and cavities to quantify spatial relationships between them. Feature content measurementsMeasurements were compared between OM, CM, and XRCT techniques to verify the efficacy of each. MicrostructuresMicrostructure near crack tips were characterized from segmented XRCT data. These data demonstrated cavity growth and interlinkage during ductile tearingTearing at 200 °C, with a larger volume fraction of internal cavities near crack tips.