Hysteretic Behavior of Twin Boundary Peak Due to Precipitation in Co-Ni-Cr alloy

Abstract

Anelastic behavior and microstructural changes of a Co-Ni-Cr super-alloy were monitored over the temperature range 250-950ºC, by using several complementary techniques. Two grades of this alloy were used, differing by the presence of small quantity of beryllium (<1.5% at.). Thermoelectric power reveals two distinct precipitation stages. The first precipitation ("A"), common to both the grades, and a second one ("B"), occurring solely in the beryllium-containing alloy. Cold-worked alloys exhibit a transient large mechanical loss peak, associated to the recrystallization of the deformed materials, and two relaxation peaks situated at around 600ºC (P1) and 780ºC (P2). Instead, only the peak P1 occurs on the fully recrystallized material. P1 and P2 can be associated to the diffusion process involved in the first precipitation stage ("A") and to the twin boundary motion, respectively. The precipitation-dissolution process of precipitates "B", localized on the twin boundary, provides a hysteretic behavior of the peak P2.

Effect of Solid Solution Temperature on Microstructure and Corrosion Resistance of CoNiCrMo Alloy

“…Co-based alloys that have excellent comprehensive properties, such as high temperature fatigue resistance, low thermal expansion coefficient, heat corrosion resistance and wear resistance, good biocompatibility, high mechanical properties and high thermal conductivity, were widely used in the fields of military, chemical industry, energy and Bioengineering [1][2][3] .…”