| Ni-Al compacts by laser-induced SHS had been synthesized in my research to fabricate Ni-Al alloys whose structure and property can be controlled, and realize the effective joint between Ni-Al alloys and stainless steel by the exothermic reaction of the systems; comprehend the transforming rules of the structure and property of Ni-Al alloys in the laser-induced SHS synthesis. Under the unbalanced conditions of laser-induced SHS, some special transformations would happen to the structure and property of materials. This research will be beneficial to the understanding of these transformations under the unbalanced conditions, and of the joint feasibility of NiAl alloys and stainless steel.Laser powers from 600W to 2000W were chosen in the experiments to fabricate different Ni-Al alloys, and to realize the SHS joint between Ni-Al alloys and stainless steel. In order to improve the structure and property of Ni-Al alloys, we added some copper in the powders. Then we analysed and measured the products'appearance, microstructure, component distributing, micro-hardness and shearing stress with the help of different instruments. From the experiments, we got some achievements below:1. The higher the laser power, the shorter the SHS ignition time, and the higher the temperature reached in the reaction. But the extra-high laser power could make the reaction more intense, and partial gathering of composition would happen in the joint regions, and more cracks and holes were found. We found in the experiments that the best joint was obtained when the laser power was 1600W. The increase of the laser power could benefit the growth of Ni-Al branch crystals. All the martensites and branch crystals were mainly in the form of Ni3Al.2. The solid-liquid diffusing reaction of Ni-Al alloys was reacted by the melting-dissoluting-separating mechanism. Both the content of Al and Cu had influences on the joint quality. The martensites created in the Ni-Al compacts were mainly Ni3Al. The branch crystals in the low Al content compacts were mainly in the form of Ni3Al, but the ones in the high Al content compacts (40at%~50at%) were maily in the form of NiAl. During the experiment, we found that the best Al content in the original compacts was between 25at% and 40at%.3. The copper content had little influence on the structure shapes. With the increase of the Cu content, the types of the products have not changed remarkably. The martensites remained in the form ofγ-(Ni,Cu)3Al, and the branch crystals in Ni-rich (Ni,Cu)Al, and the content of copper in the solid-solutions increased with the content of copper in the compacts. Martensites could be obtained by air cooling and quenching, but the ones obtained by quenching were much more and finer.4. The increase of Al could improve not only the hardness of the joint regions obviously, but also the Ni-Al substrates. So aluminum could strengthen the substrates. The addition of copper in the compacts obviously improved the density of the joint regions and the Ni-Al substrates, and enhanced the toughness, but contributed to the intensity of the joint regions and the Ni-Al substrates little. We knew from the experiments that the best addition content of copper was between 8wt% and 10wt%.5. The rupture character of the samples was brittle rupture, and the samples were brittle materials. The shearing stress of the original compacts was 8.47MPa, and the shearing stress of the compact samples after SHS reaction was 14.3MPa, with the amplitude of 68.8%. Although the shearing stress of the samples was not so high, it could satisfy the general requirements in industry.
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