Bbc Brown, Boveri & Company, Limited

Brown, Boveri & Cie Ag

Keith N Melton

Olivier Mercier

Helmut Riegger

Peter Taiana

Gunther Schroder

Roland Kunzli

Renata Sebalj

Shape-memory alloy based on copper, zinc and aluminum and process for

Fine grained copper-based or nickel-based memory alloys having a matrix of .beta.-high temperature phase with metal oxide particles dispersed in the matrix which act to retard grain growth have improved mechanical characteristics such as elongation, toughness and workability, compared to cast and worked alloys. These alloys are produced by powder metallurgy.

Memory alloys based on copper or nickel solid solution alloys having

Finished components made from Ni/Ti or Ni/Ti/Cu memory alloys can be manufactured by isothermal or quasi-isothermal ('hot die') working of sections of semifinished product, and by subsequent additional cold-working in the temperature region of the martensitic transformation by flow-turning, tapering, necking, ironing or spinning, it being possible to dispense, completely or at least to a large extent, with an additional machining operation of the metal-cutting type. Manufacture of complicated connecting elements, using the memory effect, for connecting rods, tubes, plates, etc.

Process for manufacturing a finished component from an Ni/Ti or Ni/Ti/Cu

Cu/Al and Cu/Al/Ni memory alloys having improved mechanical properties are prepared by powder metallurgy from mixtures of pre-alloyed and/or pre-mixed powder ingredients. The mixture of powder ingredients is subjected successively to isostatic pressing, sintering in an inert atmospheric and subsequent multi-step hot working with intermediate annealing which serves to homogenize. Final annealing is carried out in the .beta.-phase solid solution temperature range and the annealed article is quenched in water.

Method of producing a memory alloy

A process for the manufacture of a solid gas and vacuum tight join between components of different physical properties using a joining element comprising a memory alloy whose memory effect gives rise to the necessary contraction or dilatation stress, in particular for the connection of a hollow body of ceramic material to a metallic object. Joins comprising a memory alloy joining element result from such process having a groove and steps and at least one further metallic or non-metallic component, in particular a hollow body.

Method of joining structural elements

A brazable shape memory alloy of the .beta.-brass type comprising a mixture of copper, zinc and aluminum and nickel in an amount effective to inhibit grain growth and a process of brazing therewith.

Brazable shape memory alloys

Thermal switch, including a switching element formed of a coherently structured vitreous metal alloy. The switching element being in a vitreous-amorphous state and having a higher strength at a lower first temperature range, and in a crystalline state and having a lower strength at a higher second temperature range. A tensioning device cooperating with the switching element for exerting a force thereon which is sufficient to break the switching element in the crystalline state and insufficient to break the switching element in the vitreous amorphous state. A device for triggering a switching process in response to the breaking of the switching element in the vicinity of a transition from the first to the second temperature range. An exchangeable cassette assembly for housing the switching element, and a method for protecting circuits against overcurrents using the thermal switch.

Thermal switch with a vitreous metal alloy switching element

A thermoelectric switch having a current conducting triggering element made from a shape memory alloy exhibiting a two way temperature effect and coupled to a stressing device which exerts a force on the triggering element to thereby determine the switching temperature of the thermoelectric switch. Mechanical switching amplification is actuated by the triggering element to interrupt current flow through the thermoelectric switch.

Thermoelectric switch

A method and apparatus for the expansion of a hollow article out of a memory alloy, in which the hollow article, cooled below the transformation temperature, is mounted between two mandrels each having an opposing taper, and in a first phase is expanded on one face to the final dimension by one mandrel and is supported against a stop, whereupon the final shape is produced by pulling the other mandrel through the hollow article from the opposite face.

Method and apparatus for the expansion of a hollow article

A shape memory alloy is provided, having a base of nickel and titanium, and additionally comprising up to 30 wt.% copper, and from 0.01 to 5 wt.% of at least one element selected from the group consisting of aluminum, zirconium, cobalt, chromium and iron. A method of making the above alloys is provided, and articles made therefrom are exemplified.

Shape memory alloys

A contact arrangement for a graphite electric arc-electrode employs a contact spud composed of a metal having a high melting point and a soldering layer disposed between the contact spud and graphite electrode. The soldering layer contains at least one carbide forming metal. In one embodiment of the invention, a carbide-forming metal layer is disposed between the graphite electric arc-electrode and the soldering layer. In a preferred form of the method of making the arrangement, the soldering layer and the carbide-forming metal layer are plasma-sprayed or steamed onto the surface to be connected.

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Busslingen, Switzerland

Keith N Melton