Small punch testing of heat resistant ultrafine-grained Al composites stabilized by nano-metric Al2O3 (HITEMAL (c)) in a broad temperature range

The mechanical properties of thermally stable ultrafine-grained Al metal matrix composites dispersion strengthened and stabilized by nano-metric in-situ Al2O3 (named HITEMAL (c)) fabricated by powder metallurgy (PM) were tested by small punch testing (SPT) in a broad temperature range from a room temperature (RT) to 500 degrees C. By changes to PM approach and applied processing parameters four specific HITEMAL (c) materials with different Al grain structure, and different morphology and distribution of Al2O3 dispersoids were fabricated and characterized by transmission electron microscopy and energy-dispersive X-ray spectroscopy. The effect of microstructural features on the mechanical properties of HITEMAL (c) materials was pursued by SPT. The SPT results were compared and correlated with the results obtained by conventional tensile testing. It was confirmed that a mutual correlation of tensile test and SPT results strongly depended on the particular testing temperature. As a result of microstructural differences between HITEMAL (c) materials the correlation between tensile test and SPT results changed quite significantly for each studied material. The analysis of fractured SPT discs by scanning electron microscopy (SEM) revealed the transformation in fracture mechanism during SPT from ductile to brittle behavior as the testing temperature increased from RT to elevated temperatures. If the testing temperature was considered as a parameter, the precision of yield strength calculation from SPT results improved significantly in whole temperature range. D ata Availability: The raw/processed data required to reproduce these findings cannot be shared at this time as the data also forms part of an ongoing study. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

The mechanical properties of thermally stable ultrafine-grained Al metal matrix composites dispersion strengthened and stabilized by nano-metric in-situ Al2O3 were tested by small punch testing (SPT) across a range of temperatures. The microstructural features of the materials had a significant impact on their mechanical properties and the correlation between SPT and conventional tensile testing results varied with testing temperature. Fracture mechanisms were found to change from ductile to brittle behavior as testing temperature increased.