With the victory, the 12th-ranked Blue Devils (23-6) avenged a regular season-ending loss to the arch-rival Tar Heels last Sunday at Chapel Hill, and will play North Carolina State on Sunday.
The third-seeded Blue Devils started methodically, leading early by only 9-8, but used three short runs to build a 54-33 halftime lead, and never was in any danger in the final 20 minutes.
They shot 61 percent from the field (20-of-33), including 8-of-11 from three-point range.
They built their biggest lead at 66-43 on a jumper by reserve Nick Horvath with 12:10 left, and will seek an unprecedented fifth straight tournament title Sunday.
Daniel Ewing, who scored a career-high 32 points in the quarterfinal win over Virginia Friday night, again led the way with 19 points.
"I knew I had to be assertive going into the starting lineup," Ewing said. "I've tried to do that throughout the season, and it is paying off."
"I have ultimate confidence in Daniel," said Duke Coach Mike Krzyzewski. "As a kid, he's unbelievable. He can be just as good a player. Throughout the year, he's had good games, not 32 points, but he's had really good games for us. It doesn't surprise me that he's doing it now."
Duke went only 13-of-21 from the free throw line, but shot 54 percent (27-of-50) from the floor.
UNC (17-15), the No. 7 seeded, was hoping to be buoyed by the return of freshman center Scott May, who missed half the season because of a broken bone in his right foot, but the Blue Devils got off to a fast start and never allowed May to be a factor.
May had not played since Dec. 27. He had averaged 12.1 points and 8.6 rebounds, and was leading UNC in steals in 10 games before he was injured.
In limited action, he had four points and three rebounds.
"It was like any other Duke and Carolina game -- great intensity and very hard fought," Felton said. "They played great basketball. They shot the ball well, and executed on the offensive end."
The Tar Heels will miss the NCAA Tournament for the second straight year. Getting an NIT bid will be an improvement from last season, when they won just eight games.
Meanwhile, North Carolina State may have played itself off the proverbial NCAA Tournament bid bubble Saturday afternoon.
The No. 4 seed Wolfpack upset 10th-ranked Wake Forest, the top seed in the Atlantic Coast Tournament, 87-83, in the semifinals. They did not have a major out of conference victory, was only 9-7 in league play, and had only one major road win in league play.
"It certainly was a team victory," said Wolfpack Coach Herb Sendek. "That is the only way we've been able to win this year. Needless to say, we're very happy and proud of our effort today."
N.C. State (18-11) was aided by two major factors -- blistering three-point shooting in the second half, and an off game for Wake Forest All-American Josh Howard.
After missing his first five shots, Julius Hodge was on target later for the Wolfpack with a game-high 31 points, going 8-of-17 from the floor and 11-of-12 from the free throw line. He also had nine rebounds. Marcus Melvin added 23 points and Josh Powell had 16.
Hodge and Marcus each hit 4-of-7 shots from behind the arc, where the Wolfpack connected on 53 percent (10-of-19) of their attempts.
"We played together," Melvin said. "We really didn't worry about things we messed up on. We just moved on to the next play. We played great defense down the stretch. Whenever we needed a stop, we made that stop."
Howard, the ACC Player of the Year, finished with 21 points and added 11 rebounds, but went just 6-of-21 from the field, and was plagued by foul trouble the entire contest.
He was guarded by Hodge most of the game.
"They were playing good defense," Howard said. "I just didn't hit some open shots that I had. It happens. It happened to me earlier in the season."
N.C. State trailed, 37-33, at the break, but started quickly in the final 20 minutes. Scooter Sherrill, who had nine points, hit a three-pointer to cap a 14-2 run to them a 47-39 advantage with 14:54 to go.
Taron Downey had 18 points and Justin Gray added 14 for the ninth-ranked Deacons (24-5), who now wait for their seeding in the field of 65.
In the end, the teams were in almost a dead heat at the foul line. The Deacons went 29-0f-36. The Wolfpack went 29-of-35 at the charity stripe.
Wake Forest had an eight-game winning streak against NCSU snapped. That had been the longest such streak by either school in the 92-year history of the series.
The Demon Deacons lost to an unranked team for only the second time this season.