621.762Microprobe analysis has been applied to the boundary layers between fibers and matrix to examine the phase composition in relation to mode of extrusion for composite materials based on iron and copper as reinforced with molybdenum and steel fibers. The width of the interaction zone varies from 2 to 4 µm.The phases correspond to the phase diagrams for these systems. Fractography indicates the failure mechanism for reinforced composites under conditions of stress and strain. At the points of application of shock loads, there is planar transverse fracture in the fibers by the cleavage mechanism. The peripheral layers are subject to viscous failure in the fibers with the formation of necks. Extrusion produces plastic strain uniform throughout the fiber length, and there are no breaks in the fibers, which provides conditions for complete realization of the strength of the reinforcing phase.

621.762Microprobe analysis has been applied to the boundary layers between fibers and matrix to examine the phase composition in relation to mode of extrusion for composite materials based on iron and copper as reinforced with molybdenum and steel fibers. The width of the interaction zone varies from 2 to 4 µm.The phases correspond to the phase diagrams for these systems. Fractography indicates the failure mechanism for reinforced composites under conditions of stress and strain. At the points of application of shock loads, there is planar transverse fracture in the fibers by the cleavage mechanism. The peripheral layers are subject to viscous failure in the fibers with the formation of necks. Extrusion produces plastic strain uniform throughout the fiber length, and there are no breaks in the fibers, which provides conditions for complete realization of the strength of the reinforcing phase.The basic problem in the development of composite fibrous materials (CFM) is the compatibility between the fibers and the matrix. Maximal realization of fiber properties requires strong bonds to the matrix. Reactions at the bounding surfaces as a rule deteriorate the properties of the composite material [1,2]. Brittle intermetallides often reduce the strength of the material because the transfer of the load from the matrix to the fibers deteriorates, and cracks are formed at the fiber-matrix interfaces. Interactions between components in the reinforced system enable one on the one hand to control the process [3] and on the other enable one to establish the temperature and time ranges for shorttime and long-time strength in the material. Component interactions in a composite fibrous material of metal-metal type should be based on the corresponding phase diagrams, but one must also consider the specific features of the surface reactions.Our purpose was to examine the compatibility of fibers and matrix in composite materials made by extrusion. We prepared specimens for metallography (D = 18.5 mm, H = 15 mm, volume fraction of fibers V = 25%) by reinforcing iron and copper powders with fibers made of steel 55 (d = 0.28 mm, I 0 /d 0 = 20) and molybdenum of MCh grade (d = 0.12 mm, I 0 /d 0 = 30). The heating during the extrusion was performed in hydrogen at T e = 850°C (copperbase specimens) or T e = 1150°C (iron-base ones), with hold for t = 15-20 min; the drawing coefficient λ = 5. This technology [4] gives an almost nonporous structure.The interaction zone was examined by electron-probe microanalysis (EPMA) with a JXA-5 apparatus (Japan); the etchant was a 4% solution of HNO 3 for composites based on iron or an 8% solution of CuCl in ammonia for composites based on copper. Figure 1 shows the microstructure of a copper − Mo fiber composite. The hardness of the interaction zone was on average 2000-2600 MPa. The hardness of the copper in the contact zone was about 1500 MPa, while that of the molybdenum was 4700 MPa. The shearing strength of the joint as a rule exceeded that of copper. There are also zones with sharp boundaries and ...