NbC was used as reinforced particles in the fabrication of iron-base composite. Ball milling was introduced to overcome the problems of agglomeration and powder separation during powder mixing. After ball milling, the fine NbC particles are embedded on the surface of iron particles and evenly distributed in the mixed powders. Warm compaction was used not only to increase the green density but also to improve the formability of the mixed powder and to improve the compact 's green strength to facilitate handling. The influences of fabrication parameters such as ball milling time, annealing temperature and time, warm compaction temperature, sintering temperature and sintering time were studied. Compacts with a relative sintered density of 97% and a tensile strength of more than 800MPa can be obtained by using a ball milling time of 5h, an annealing temperature of 800℃, a compaction pressure of 600MPa, warm compaction temperature of 120℃, sintering temperature of 1280℃, and sintering time of 80min. The shrinkage at this sintering condition was approximately 4.3%.

Effects of different sintering temperature and sintering time on the relative density of the sintered compacts were studied to obtain the optimal sintering parameters for the fabrication of NbC particulate reinforced iron-base composite. With optimal sintering temperature of 1280℃ and sintering time of 80min, wear-resisting, high density NbC particulate reinforced iron-base composites can be obtained using warm compaction powder metallurgy. The microstructure, relative density, mechanical properties and tribological behaviors of the sinter ed composites were studied. The results indicate that the mechanical properties of the sintered compacts were closely related to the sintered density. The iron-base composite materials with different combinations of mechanical properties and tribological behaviors were developed for different applications. One of the dev eloped composite, which contains 10%NbC, possesses a high strength of 815MPa with a remarkable friction and wear behaviors. The other developed composite, which contains 15%NbC, possesses a lesser strength of 515MPa but with excellent friction and wear behaviors.

The tensile plastic deformation behavior of B2-ordered Fe₃Al single crystals at room temperature was systematically investigated. The results show that the mechanical properties are strongly orientation dependent. The plastic elongation of crystals with orientation near ［110］ is as high as 42%. Slip trace analysis shows that although slip planes are found to change among {110}, {112} and {123} with the change in orientations, the initial slip planes in allcases are {110}. Five-stage work hardening curve including four linear stages and one parabolic stage is obtained; but not all stages are observed in the actual deformation of each crystal. In combination with investigations of dislocation substructure, it is found that deformations in stage Ⅰ～Ⅲ are corresponding to the motion of two-fold superdislocations. The higher work hardening rate of stage Ⅱis mainly due to the stronger interactions between primary dislocations and secondary dislocations than those in stage Ⅲ. Deformation in stage  involved is not only the motion of two-fold superdislocations but also the slip of dissociated superpartials with APB traps and the formation of APB tube, both of which are attributed to the hardening. Deformation in stage  Ⅴ is controlled by the cross slip of dissociated superpartials. The dominated softening effect of cross slip reduces the hardening rate and leads to the formation of parabolic stage.