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In recent years, functionally gradient materials have been developed. But we seldom see the paper about that FGMs are produced by making use of laser. In this paper, we make FGMs with laser in self-propagating high-temperature synthesis. We select nickel and aluminum powders, which can react and release much heat. The ignition time and reaction time are shortened. And the highest temperature which reaction can get is improved. Utilizing the laser of high power density, we can get more complete product. And the composite process of phase in this method is different from that in tradition method. Functionally graded materials (FGMs) are materials in which certain properties change continuously from one surface to the other. The preparation of FGMs has been performed by a number of techniques, related to both ceramics and metal processing which have been widely discussed in the international meetings on this subject, and summarized in some papers. 1,2) The methods so far used to produce FGMs have included chemical and physical vapor deposition, 3) powder metal- lurgy, 4) plasma spray and self-propagating high-temperature synthesis (SHS). 5) All these methods have some drawbacks. In these methods, SHS is increasingly used owing to the lower cost and better availability of starting materials, simple processing equipment, and lower energy consumption result- ing from less heat input and shorter processing times and higher product purity because of less reaction during the processing. 2) SHS is a general processing technique in which reactants, usually elemental constituents, when are ignited, spontaneously transform to products as a result of the exothermic heat of formation. The steps involved in SHS are reactant powders preparation, cold compaction and occur either as a wave propagating across the specimen from a single ignition source or as volumetric combustion where the reaction is ignited at multiple sites throughout the specimen as a result of uniform heating of the entire specimen. The combustion wave velocity and stability control the level of porosity and uniformity of the product phase. The combus- tion wave can be controlled by the heating rate, reactant particle size, shape and distribution, specimen green density and diameter, conductive cooling, the addition of pretreated diluents and externally applied pressure.

Ni-Al Functionally Graded Materials by Laser Self-Propagating High-Temperature Synthesis