Armstrong, the special teams coordinator of the Falcons, will interview with Arizona for a second time on Friday, Ian Rapoport of the NFL Network reported.
The Cardinals reportedly have interviewed nine assistant coaches for the position and, per the Arizona Republic, six are still in the running to succeed Bruce Arians.
Other candidates are two coaches with the Philadelphia Eagles -- defensive coordinator Jim Schwartz and quarterbacks coach John DeFilippo -- along with Cardinals defensive coordinator James Bettcher, New England Patriots linebackers coach Brian Flores and Carolina Panthers defensive coordinator Steve Wilks.
Pittsburgh Steelers offensive line coach Mike Munchak on Wednesday declined a second interview with Arizona, citing family issues.
Armstrong just completed his 10th season with Atlanta. His coverage units routinely are ranked among the league's top 10. Prior to joining the Falcons, Armstrong spent seven seasons in a similar capacity with the Miami Dolphins.
Arians, 65, retired on New Year's Day after five seasons as the team's head coach. He owned a 49-30-1 mark with the Cardinals and was a two-time NFL Coach of the Year recipient, capturing the honor in 2012 with the Indianapolis Colts and 2014 with the Cardinals.