Abstract: A contact piece is formed by a tungsten overlay soldered onto a support, wherein at least portions of the solder layer and optionally of the support are covered by a layer of a less noble metal than tungsten. The corrosion resistance of the tungsten overlay is considerably improved.

Abstract: The present invention relates to powder-metallurgically produced composite material comprising a matrix of a metal with a melting point of at most 1,200° C. and a granular additive which consists of at least two refractory components embedded in said matrix, characterized in that the refractory components are present as mixed crystals or intermetallic phases. In one embodiment of the invention one or a first group of refractory component(s) has a melting point in the range of 1,500 to 2,400° C. and the second or the second group of refractory component(s) has a melting point above 2,400° C. The composite material is produced by heating a pulverized mixture of the refractory components, thus converting it into a mixed crystal or an intermetallic phase, and then combining the powder obtained by cooling and pulverizing with a metal matrix having a melting point of at most 1,200° C. by means of powder-metallurgy.

Abstract: The present invention relates to a powder-metallurgically produced composite material comprising a matrix and a granular additive comprising at least one fine-grained refractory metal with an average grain size of at most 2 &mgr;m uniformly distributed in the matrix, so that the composite exhibits a residual porosity of <0.5%. Furthermore, the invention relates to a method for the production of the composite and its use as an electrical contact material.