The Tar Heels (28-4) will take on North Carolina State in Saturday's semifinals after the Wolfpack pulled off a mild surprise with a 67-64 triumph over Virginia.
No. 6 Duke had a tougher time than expected but the Blue Devils got past Virginia Tech 60-56 to set up a semifinal meeting with Florida State, which defeated Miami 82-71.
North Carolina had a balanced attack and broke the game open early in the second half. James Michael McAdoo and Tyler Zeller each had 14 for the Tar Heels and Kendall Marshall had 13 points and 12 assists.
Maryland (17-15) got 30 points from Terrell Stoglin, who was 5-of-11 from 3-point range.
North Carolina State overcame shaky free-throw shooting down the stretch in beating Virginia. The Wolfpack was just 5-of-10 over the final 2:02, but it was enough to hold off the Cavaliers (22-9).
C.J. Leslie had 19 points and 14 rebounds for North Carolina State while teammates Lorenzo Brown and Richard Howell, added 15 and 10 points, respectively. Mike Scott had 23 points and 11 rebounds and Akil Mitchell had 10 points and 11 rebounds for Virginia.
Duke, seeking its fourth consecutive ACC Tournament title, opened a 10-point lead with less than 6 minutes remaining and held on thanks in part to 17 points from Austin Rivers.
Tyler Thornton had 13 points and Mason Plumlee added 12 and 11 rebounds for the Blue Devils (27-5).
Virginia Tech (16-17) was paced by 16 points from both Erick Green and Robert Brown.
Florida State (22-9) pulled away late after Miami had closed within three with 4:14 to play. The Seminoles were paced by Michael Snaer with 20 points and Ian Miller with 17.
Miami (19-12), which had a regular-season victory over Duke and split its two previous meetings with Florida State, picked up 19 points from Malcolm Grant.