Contribution of the Interfacial Reaction to the Strength of Molybdenum and Tungsten Fiber-reinforced Composites

Abstract

Relation between the mechanical properties and interfacial reaction of composites containing tungsten or molybdenum fibers in the copper alloy matrix was investigated. The composites were prepared by infiltration and hot pressing methods. The thickness of the reaction zone in composites which was detected from electron microprobe examination was regulated by changing the annealing time at 850°C. The strength and Young’s modulus of composites were measured by an Instron type tensile machine at room temperature.
The results obtained were as follows:
(1) The mechanical properties of composites with Cu–Ni and Cu–Mn alloy matrices prepared by the infiltration method were damaged by the products of fiber-matrix reaction and recrystallization of fibers.
(2) Nickel and manganese have been added to the copper matrix so that the reaction zone was formed at the fiber-matrix interface. The thickness of the reaction zone in hot pressed composites was regulated quite easily by changing the annealing time.
(3) An appropriate thickness (5∼10 μ) of the reaction zone at the interface contributed to the improvement of the strength of composites. The thickness of the reaction zone increased further, the strength decreased rapidly.
(4) A positive contribution of the reaction zone to the strength of the composites whose orientation lay on 15° and 30° was also observed.