Q.W. Wang

Formation of intermetallic compound layer in multi-laminated Ni–(TiB2/Al) composite sheets during annealing treatment

Solid-state reactive diffusion between Ni and Al was investigated during annealing at 650°C by employing multi-laminated Ni-(TiB(2)/Al) composite sheets. In multi-laminated Ni-(TiB(2)/Al) composite sheets annealed up to 5min NiAl(3) was the only phase observed in the diffusion zone, and Ni(2)Al(3) appeared after longer annealing time. Most grains of Ni(2)Al(3) showed equiaxed morphology rather than columnar microstructures like NiAl(3), due to the low concentration gradients of Al and Ni at the Ni/NiAl(3) interface. The preferential formation of this intermetallic compound NiAl(3) in multi-laminated Ni-(TiB(2)/Al) composite sheets was predicted using an effective heat of formation model. The present work indicated that both Ni and Al interdiffused, and the formation of NiAl(3) was a reaction-diffusion process.

Microstructure and Reaction Mechanism of Multi-Laminated Ti-(SiCp/Al) Composites Subjected to Annealing at 1300°C

The multi-laminated Ti-(SiCp/Al) composite was produced by hot press and subsequent hot roll bonding of Ti and SiCp/Al foils. The microstructure evolution of the composite in reaction annealing was investigated by scanning electron microscope (SEM) equipped with energy dispersive X-ray spectrometer (EDX) and X-ray diffractometer (XRD). The results show that after the reaction annealing at 1300°C for 3h, the Ti and SiCp/Al foils were completely consumed and transformed into the TiAl composite with a microlaminated structure. The microlaminated microstructure of the composite is composed of Ti3Al/(TiAl+Ti5Si3p)/Ti5Si3/duplex-phase (TiC+Ti3AlC) layers. The reaction mechanism is elucidated by employing the reaction model.

Effect of Milling Parameters on Morphology and Grain Size of WO3 and Al Particles for Fabricating WO3/Al Composites

In this paper, the milling process of WO3 and aluminum particles is studied. Influences of rotate rate, milling time and ball-to-powder weight ratio on the morphology and grain size of the particles are studied by scanning electronic microscope and X-ray diffraction techniques. Al particle size decreases firstly and then increases with increasing milling time, while Al grain size decreases gradually as the milling time increases. WO3 particle is distributed uniformly in Al particles after milling for 9h, and has no marked change as further extension of milling time. With increasing the ball-to-powder weight ratio and rotate rate, both particle size and grain size of Al decreases. milling parameters have almost no effect on the grain size of the WO3 particles.