Plumlee was coming off a career-high 28 points on 9-of-11 shooting from the field, 10 of 11 from the free-throw line and had nine rebounds in the Blue Devils' previous game, an 88-67 win over Florida Gulf Coast.
Sophomore point guard Quinn Cook had a career-high 17 points for the Blue Devils, who extended their regular-season tournament winning streak to 21 games, a run that stretches to the championship game of the 2006 CBE Classic.
Duke (4-0) will face the winner of the first-round game between No. 19 Memphis and VCU in Friday's semifinals.
Rodney Williams had 16 points for the Golden Gophers (4-1), who just couldn't cut into the Blue Devils' lead in the second half.
Duke's lead ranged from 10 to 13 points throughout most of the second half. Minnesota, a team known for its toughness and defense, met its match in the Blue Devils, who were just as physical as the Gophers, and were more so through the last 5 minutes when Duke pulled away.
Curry was 8 of 11 from the field and Duke finished 30 of 55 (54.5 percent). Curry made all three of his 3-point attempts, and the Blue Devils were 8 of 10 from beyond the arc.
Minnesota had held its first three opponents to 28.6 shooting from the field and 19.1 percent on 3s while giving up 48.0 points per game. Obviously, Duke was a little bit better than the Gophers' first three opponents.
This was Duke's 150th consecutive game ranked in the top 10, and the Blue Devils are 150-30 in those games.