Abstract: A method of making a transparency is provided, the method comprising the steps of: layering at least two pieces of transparent thermoplastic, wherein a portion of at least one of the pieces of transparent thermoplastic is treated with a near infrared absorbing material; and, fusing the layered pieces of transparent thermoplastic together using a heat source to form an optically transparent and undistorted transparency. There is also provided a transparency comprising at least two layers of transparent thermoplastic, wherein the layers of transparent thermoplastic have been fused together using a heat source, such that the transparency is optically transparent and undistorted.

Abstract: A zone of corrosion-resistant material covering a friction stir welded joint surface is provided by applying a layer of corrosion-resistant material over one or both surfaces of the workpieces being joined so that the layer covers at least the weld zone which will be rendered plastic during a friction stir welding operation. The corrosion-resistant material layer is contacted by the friction stir welding tool, and the tool causes shearing and plastic flow of the corrosion-resistant material along the surface of the welded joint. The corrosion-resistant material thus metallurgically bonds with portions of the plasticized metal so as to form a corrosion-resistant zone protecting the welded joint from exposure to corrosive environments.