The alto saxophone is not exactly an unfamiliar instrument, but its achievements in classical music still lag behind its accomplishments in jazz. Saxophonist Christopher Ford has not raised his instrument to the classical status of the violin, but he scored a few significant points for it in a well-played recital yesterday afternoon in the Renwick Gallery.

He played a varied and engaging program of modern music (there is not much of enduring value for the saxophone written before this century), and he gave the Washington premieres of two pieces that significantly expand the instrument's expressive range: Charles Wuorinen's Divertimento and Michael Maloney's Music for Flute, Saxophone and Tape. His interpretation of Ibert's Concertino da Camera (one of the few solidly established classics for the instrument) was brilliant, and he exploited effectively the melodic riches of three slight but melodious works: Paul Maurice's folk-flavored "Tableaux de Provence," Paul Creston's lyric and energetic Sonata, Op. 19, and the jazz-tinged Prelude, Cadence et Finale of Alfred Desenclos.

Wuorinen, who is best known for his intensive cultivation of serial forms, sounds a lot less strict, more lyric and spontaneous in the Divertimento than in many of his other works. He uses the resources of the saxophone with a fine sense of color, moving rapidly among growling, low vibrato, piercing high notes and a warm, mellow bass sound. The music blends lyric and declamatory styles, and the piano has as interesting a part as the sax, though pianist Mary King's work yesterday was more notable for precision than for drama.

Maloney's piece, in which Aimee Ford was the flutist, uses harmonic and melodic motifs from Irish folk music in a highly distilled form with substantial impact.