Investigation of the two martensitic phase transitions hcp-dhcp and dhcp-fcc in Co-0.85at%Fe by neutron scattering

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Structural materials : properties, microstructure and processing, 1998-12, Vol.273-275, p.491-493
• Main Authors: Prem, M, Krexner, G, Blaschko, O
• Format: Article
• Language: English
• ISSN: 0921-5093

Upon heating, Co-0.85at%Fe undergoes the two martensitic phase transitions hcp - > dhcp (at approx =590 K) and dhcp - > fcc (at approx =690 K). The transitions are characterized by a large hysteresis permitting to investigate properties of two phases at the same temperature, respectively. The distance between neighboring close-packed planes remains virtually constant during the hcp-dhcp transition while a change of approx =0.3% is observed at the dhcp-fcc transformation. The lattice dynamics of Co-0.85at%Fe was investigated by means of inelastic neutron scattering at a series of temperatures up to 750 K in order to look for precursor effects in the phonon dispersion curves near the two martensitic transformations. In all of the phonon branches investigated, anomalies were neither found near the hcp-dhcp nor the dhcp-fcc transition. Both transformations in this system occur slowly and with a continuous change of the volume fractions of the phases involved over periods of several hours.