Pengchao Kang

Microstructure of multilayer interface in an Al matrix composite reinforced by TiNi fiber.

A multilayer interface was formed in the Al matrix composite which was reinforced by 30% volume fraction of TiNi fiber. The composite was fabricated by pressure infiltration process and the interface between the TiNi fiber and Al matrix was investigated by transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS). When the TiNi fiber was pre-oxidized in the air at 773 K for 1 h, three layers have been found and characterized in the interface: TiNi-B2 layer near the TiNi fiber, Ti-Al compound layer with Ti and granular TiO2 near the Al matrix, and Ti-Ni compound layer between TiNi-B2 and Ti-Al compound layers. The effect of the multilayer interface on the mechanical properties of the composite was also discussed. The result showed that the uniaxial tensile strength of the composite at room temperature was 318 MPa, which was very close to the theoretical calculation value of 326 MPa. Moreover, the composite with good ductility exhibited a typical ductile-fracture pattern.

Effect of heating process on fracture behaviors of Wf/Cu82Al10Fe4Ni4 composites

Wf/Cu82Al10Fe4Ni4(30) composites and Wf/Cu82Al10Fe4Ni4(60) composites were prepared by penetrating casting method. Three-point bending test and dynamic compression test showed that Wf/Cu82Al10Fe4Ni4(30) composites possessed higher mechanical properties than Wf/Cu82Al10Fe4Ni4(60) composites. Microstructure observation of Wf/Cu82Al10Fe4Ni4(30) composites revealed that a small amount of tungsten diffused into the Fe–Ni solid solution precipitated on the surface of tungsten fibers. The damage occurred mainly within the tungsten fibers after three-point bending test and dynamic compression test in Wf/Cu82Al10Fe4Ni4(30) composites, indicating that the composites possessed high interface strength. Dislocation density was high and stacking faults emerged in Wf/Cu82Al10Fe4Ni4(30) composites after dynamic compression. Microstructure observation of Wf/Cu82Al10Fe4Ni4(60) composites revealed that long strip of tungsten grains occurred at the edge of tungsten fibers, within which damage mainly emerged after three-point bending test, indicating that strength of the edge of tungsten fibers was low in Wf/Cu82Al10Fe4Ni4(60) composites. The fibrous structure of tungsten fiber was coarse or even disappeared in some areas, and dislocation density was low in Wf/Cu82Al10Fe4Ni4(60) composites after dynamic compression.