Mike Krzyzewski was named last night to become basketball coach at Duke, replacing Bill Foster, who resigned to coach at South Carolina.

Krzyzewski, 33, has been the coach at Army the past five seasons, compiling a 73-59 record, including 9-17 this season. The two previous seasons, Army was 20-8 and 19-9.

The choice of Krzyzewski was a surprise. It had been believed that Duke had narrowed its choices to Foster's top assistant, Bob Wenzel, and Mississippi Coach Bob Wetlich. The team supported Wenzel, as did many alumni.

But while speculation centered on Wenzel and Weltlich, Athletic Director Tom Butters met secretly with Krzyzewski on four different occasions to discuss the job.

Krzyzewski was a point guard at Army when Bobby Knight was coach during 1967-1969. He served in the Army for five years after graduation before taking over the faltering West Point program in 1975.

Last summer he was an assistant coach under Knight on the U.S. Pan American team. His Army teams received one postseason bid, playing in the 1978 NIT.

Krzyzewski is a Knight disciple; his teams are known for agressive defense and a controlled style of play. At Duke, however, with more talent, Krzyzewski may opt for a less conservative offense.

Butters had named four coaches as having interviewed for the job: Wenzel, Weltlich, Paul Webb of Old Dominion and Tom Davis of Boston College.