2024/03/19 by Anwesha Kanjilal, Ali Ahmadian, Kanjilal, Anwesha +11
Engineering · Materials Science · #Advanced ceramic materials synthesis #Aluminum Alloys Composites Properties #FOS: Physical sciences #Intermetallics and Advanced Alloy Properties #Materials Science (cond-mat.mtrl-sci)
paper · pdf · doi:10.48550/arxiv.2403.12507
openalex publication_date 2024/03/19 · openalex created_date 2024/03/21 · openalex updated_date 2026/07/28
The influence of temperature on the deformation behaviour of the C15 CaAl2 Laves phase, a key constituent for enhancing the mechanical properties of Mg alloys up to service temperatures of 200 °C, remains largely unexplored. This study presents, for the first time, the nanoscale brittle-to-ductile transition (BDT) of this intermetallic phase through in situ testing including nanoindentation, scratch testing, and micropillar splitting conducted at elevated temperatures. By correlating observations from these techniques, changes in deformation of CaAl2 were identified in relation to temperature. High-temperature nanoindentation quantitatively determined the temperature range for the BDT, and revealed that CaAl2 undergoes a BDT at ~0.55Tm, exhibiting an intermediate region of microplasticity. A noticeable decrease in nanoindentation hardness was observed at ~450-500 °C, accompanied by an increase in residual indent size, while indentation cracking was not observed above 300 °C. Results from high-temperature micropillar splitting revealed cracking and brittle pillar splitting up to 300 °C, with an increase in apparent fracture toughness from 0.9 ± 0.1 MPa⋅√ m to 2.8 ± 0.3 MPa⋅√ m, and subsequent crack-free plastic deformation from 400 °C. Transmission electron microscopy analysis of the deformed material from nanoindentation revealed that the BDT of CaAl2 may be attributed to enhanced dislocation plasticity with increasing temperature.