Pii: S1359-6454(99)00308-0

ÐThe longitudinal primary creep of long-®ber composites is modeled by considering the transient stress states arising from load transfer from the weaker matrix phase to the stronger ®ber phase as the composite transitions from the elastic state present immediately after loading to steady-state stage where both phases creep. The e€ect of primary creep of each of the phases on the primary creep of the composite is also taken into account. The model is evaluated for the NiAl±W system for which the primary creep of tungsten ®bers is quite signi®cant. The composite primary creep strain is predicted to be signi®cant at high applied composite stresses and for high ®ber volume fractions and primary creep time is found to be uniquely related to the composite steady-state creep rate. The model is veri®ed with 10258C compressive creep experiments in the NiAl±W composite system. Good agreement between model predictions and experiments is obtained when the observed composite steady-state creep behavior converges to the steadystate predicted for materials in which both phases experience creep deformation. # 1999 Acta Metallurgica Inc. Published by Elsevier Science Ltd. All rights reserved.