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Titanium and zirconium carbide layers were produced on the surface of graphite fibers. The process allows a controlled reaction of the fibers with the carbide-forming elements dissolved in a molten tin bath, which acts as the transferring medium. The coatings were analyzed by optical and scanning electron microscopy, energy dispersive X-ray analysis, and X-ray diffraction. It was found that they consist of two distinct layers, one with the binary carbide composition in contact with the fiber core and an exterior one having a ternary carbide composition. The coatings are brittle, continuous, and uniform along and across the fibers and show good adherence to the carbon core. The carbide growth process is difF'usion-controlled with an activation energy of 184 kJ/mol. The coated fibers are readily wetted by molten aluminum.

The tensile properties of ordered and disordered Ni,Fe single crystals have been investigated. Also, polycrystalline specimens have been tested to show the influence of grain size on the deformation characteristics of Ki,Ye. Mcasurernents have been made to determine the influence of parameters such as the initial orientation of the tensile axis of single crystals, the ordered domain size, and the test temperature on the mechanical properties of Ni,Fe. Tensile axis reorientation during deformation was followed with X-ray techniques.It was found that in ordered single crystals. the measured tensile axis rotation agrees well with the calculated values if one a,ctivated glide system is assumed. The influence of secondary slip on the tensile characteristics of ordered crystals was determined by using specimens oriented for multiple glide. It is demonstrated that the work hardening rate increases with the occurrence of secondary slip. The strain-aging phenomena shown previously in polycrystalline Pu'i,Fe was found to occur also in single crystals. The nature of the observed effects in ordered Ni,Fe is interpreted in terms of the antiphase boundary tube mechanism.Les propriet6s sous tension des monocristaux ordonnt?s et desordonnes de Ni,Fe ont Btt? Btudiees. Des experiences ont aussi BtB faites sur des specimens polycristallines pour montrer l'influence de la taille du grain sur les caracteristiques de la deformation de Ki,Fe. Des mesurages ont Bt6 faits afin de determiner l'influence des parametres tels que: l'orientation initiale de l'axe de tension des monocristaux, la taille de domaines ordonnbs et la temperature de mesurage sur les proprietes mecaniques de Ni,Fe. La &orientation de l'axe de tension pendant la deformation a btit suivie avec des rayons X-techniques. I1 a 6t6 trouv6 que dans les monocristaux ordonnes, la rotation de l'axe de tension mesurCe est en accord avec les valeurs calculees si un systbme de glissement est active. L'influence de glissement secondaire sur lea caracteristiques des monocristaax ordonnks a irtt? determin6e en utilisant des specimens orient& pour glissement multiple. I1 est demontrt? que la vitesse d'6crouissage augmente avec la presence de glissement secondaire. I1 a 6tB trouv6 que le ph6nomiine de vieillissement sous tension d6jA observe dans polycristalline Ni,Pe se produit aussi dans les monocristaux. La nature des effets observks dans Ni,Fe ordonne est interpr6tee avec le mecanisme de production des tubes de frontieres de domaines antiphases.