Abstract: A rewritable optical information medium has a phase-change recording layer (3) on the basis of an alloy of Ge-Sb-Te-O, having the composition (Ge.sub.a Sb.sub.b Te.sub.c).sub.1-d O.sub.d, wherein:a+b+c=10.0001 a d a 0.035The addition of oxygen considerably speeds up the crystallization rate of Ge-Sb-Te materials. Such a medium is suitable for high speed recording (i.e. at least eight times the CD-speed), such as for DVD-RAM and optical tape. The amount of oxygen in the recording layer (3) can be used to tune the crystallization rate to the desired value.

Abstract: An Invar type alloy on the basis of iron is formed by an intermetallic compound having a cubic crystal structure of the NaZn.sub.13 type having a nominal composition La(FeCoX).sub.13, wherein X is Si or Al. By subjecting the present intermetallic compound after melting to a tempering treatment at 800.degree.-1,000.degree. C. and cooling it in an accelerated manner, a brittle material is obtained which can be ground to form a powder. From this powder, articles having any desired (optionally complicated) shape can be produced by means of powder metallurgy. By mixing powders of two different intermetallic compounds, a material can be obtained having a substantially negligible coefficient of linear thermal expansion in the temperature range from 0.degree. C. to 200.degree. C.

Abstract: A method of and a device for soldering components on thick-film substrates according to the reflow method. Successively, the substrates are preheated, followed by heating to the soldering temperature, after which they are cooled. A wave of molten metal of a given temperature is used for preheating, heating and cooling of the substrates.