Mechanical properties of in situ consolidated nanocrystalline multi-phase Al–Pb–W alloy studied by nanoindentation

Abstract

Formation of chunks of various sizes ranging between 2 and 6 mm was achieved using high-energy ball milling in Al–1at.%Pb–1at.%W alloy system at room temperature during milling itself, aiding in in situ consolidation. X-ray diffraction and transmission electron microscopy (TEM) studies indicate the formation of multi-phase structure with nanocrystalline structural features. From TEM data, an average grain size of 23 nm was obtained for Al matrix and the second-phase particles were around 5 nm. A high strain rate sensitivity (SRS) of 0.071 ± 0.004 and an activation volume of 4.71b³ were measured using nanoindentation. Modulus mapping studies were carried out using Berkovich tip in dynamic mechanical analysis mode coupled with in situ scanning probe microscopy imaging. The salient feature of this investigation is highlighting the role of different phases, their crystal structures and the resultant interfaces on the overall SRS and activation volume of a multi-phase nc material.

Keywords:

• Nanocrystalline
• In situ consolidation
• strain rate sensitivity
• multi-phase
• activation volume
• modulus mapping

Acknowledgements

This work was supported by the Department of Science and Technology, Government of India under fast track scheme for young scientists. SreedeviVaram would like to thank the University Grants Commission (UGC), New Delhi, India for providing her with the Junior Research Fellowship in Engineering and Technology. The experimental facilities used in these investigations at University of Hyderabad are supported by the DST-PURSE program of Government of India.