|About this Abstract
||MS&T21: Materials Science & Technology
||Nucleation of Solid-State Phase Transformations
||Formation of the γ’’’-Ni2(Cr, Mo, W) Phase during Two-step Heat Treatment in Haynes® 244® Alloy
||Thomas Mann, Michael Fahrmann, Michael Titus
|On-Site Speaker (Planned)
Several nickel alloys containing molybdenum and chromium have shown short range order (SRO) from cooling after a solution anneal heat treatment. This short range order includes DO22, DOa, and Pt2Mo type phases that can evolve into long range order (LRO) domains that increase the strength of the alloy. Haynes® 244® has shown this short range order to long range order transition resulting in the γ’’’-Ni2(Cr, Mo, W) phase, which significantly strengthens the alloy. Previous studies have shown the transformation to be a precipitation transformation at higher aging temperatures and a continuous ordering transformation at lower aging temperatures. This study investigates the use of a two-step aging treatment to rapidly age the alloy resulting in LRO of the γ’’’-Ni2(Cr, Mo, W) phase. The formation behavior and SRO to LRO transition were investigated using small-angle x-ray scattering and electron microscopy. Optimizing the aging heat treatment schedules and strength will be presented.