There are signs that a whopping crop of musicians is coming to maturity in the '80s. Violinist Stacy Phelps, making her first appearance at the Phillips Collection yesterday afternoon, would seem to be among them. Her confidence borders on fearlessness, and her fluency approaches glibness.

The 25-year-old artist won the upper string division of the Friday Morning Music Club's 1982 International Competition.

The program yesterday offered plenty of challenges, from Bach's Partita No. 2 through sonatas by Bloch and Debussy to a closing flourish of Sarasate pieces and a Barto'k Rhapsody. Phelps maintained a consistently singing tone and strongly centered pitch, taking the time to give lines space and a personal inflection--a bit too much, in fact, in the Bach. As some lagging moments in the Bloch Sonata indicated, she will want to think more about subordinating moments of beauty into a larger scheme, if she is to deepen her art. She brought an infectious touch of humor to the Sarasate technical displays and a welcome, if not quite sharp enough, bite to the Debussy and Barto'k works. Her sister, Sheila Phelps Johns, made a most sympathetic and able accompanist.

The program will be broadcast on WETA-FM at 10 a.m. Nov. 23.