  Upcoming projects requiring high-Q ~650 MHz medium-to-high-${\beta}$
elliptical cavities drive a need to understand magnetic RF loss mechanisms and
mitigations in greater detail. High-temperature annealing and fast-cooldowns
have proven effective techniques for promoting magnetic flux expulsion in
cavities, however the extent of their effectiveness has been observed to vary
between niobium material lot and vendor. We explore the fast-cooldown method,
and high-temperature annealing (900{\deg}C) in 644-650 MHz cavities fabricated
from two different niobium vendors: Tokyo-Denkai, and Ningxia. which promote
flux-expulsion efficiency. Using EBSD and PPMS methods, we aim to trace cavity
flux expulsion efficiency to specific, measurable properties of the bulk
niobium material, which, if identified, can lead to methods by which the flux
expulsion properties of Nb material can be predicted prior to cavity
fabrication, and can enable fine-tuning of cavity temperature treatments.
