Abstract: The surface area of a rectangular semiconductor substrate (10), which is used a reference plane, is composed of three regions arranged side by side in its lengthwise direction. A first one of the regions has a concavity (13) formed leaving opposite marginal portions of the region as banks (14a,14b), aid solder-coated pads (17) and alignment marks (18) are formed by metal thin films on the top surfaces of the banks. In a second region an electrode (16) is formed adjacent the first region and a semiconductor optical element (PD4) is mounted on the electrode with an active layer (31) of the former facing downward. An under-clad layer (211), acore (22), a height adjustment layer (26) and an over-clad layer (212), which constitute an optical waveguide, are formed over the surface of a second substrate, and the over-clad layer overlying both marginal portions of the second substrate is removed to expose the height adjustment layer to form terraces (20a, 20b) corresponding to the banks.

Abstract: Disclosed are Ti-Al alloys having increased ductility and Ti-Al alloys having increased ductility and lowered melting points, in both of which the main constituent phase is an intermetallic compound, TiAl.The Ti-Al alloys having increased ductility essentially consisting of Al: 28-38%, and B: 0.005-0.3%, the balance being Ti and inevitable impurities.Since the alloys of this type have good processability, they are suitable as materials for mechanical parts of rotating or reciprocating systems, where high heat-resistance and high specific strength are required.The Ti-Al alloys having increased ductility as well as lowered melting points essentially consisting of Al: 28-38%, one or two of Ni: 0.05-3.0% and Si: 0.05-3.0%, and the balance being Ti and inevitable impurities. Optionally, this alloy further contains B: 0.005-0.3%.The alloy of this type is, in addition to the above use, suitable for producing machine parts made by precision casting technology.

Abstract: A composite follow valve for internal combustion engines such as an intake and an exhaust valve and the method for producing the same are disclosed. The valve is produced by integrating into the whole a valve head portion molded from a lightweight, heat-resistant material selected from a group of titanium alloys and titanium-aluminium alloys, a stem portion molded from a high-strength alloy steel, made hollow inside to reduce weight, and a stem end portion molded from a hard material selected from a group of martensitic stainless steel, silicon nitride and silicon carbide ceramics. Since the different materials of the separate valve components are selected to meet the requirements of their particular functions and operating condition under which they are placed. Also, because of this separate arrangement, the valve can be produced at a relatively reduced cost, since the use of expensive materials is saved.