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Home Material Sciences Nanostructured Shape Memory Alloys Elaborated By The Glass Devitrification And Powder Metallurgy Processes

Nanostructured Shape Memory Alloys Elaborated By The Glass Devitrification And Powder Metallurgy Processes

Description

Conventionally produced shape memory intermetallic compounds with enhanced transformation temperatures are often brittle, so, non-equilibrium processing techniques are provided for the production of amorphous precursors or nanocrystalline materials together with micro and macro alloying. The (TiZrHf)(NiCuMe) melt-spun ribbons and twin-roll strips with controlled grain size and small size dispersion have been obtained from initially amorphous state by appropriate heat treatments. Pre-alloyed TiNi-base powders have been obtained by the electric-spark erosion technique providing solidification rates of 106–109K/s from liquid and vapor states. Ni-Mn-Ga-X alloys powders by electric spark erosion and ultrasonic assisted severe plastic deformation by ball milling are also envisaged. Details of the processes used and enhancement of shape memory properties due to the nanoscale crystals formed from supercooled metallic liquid or broking microstructure dawn into nanostructured will be carefully studied on modern equipment.

Innovative Aspect and Main Advantages

Problem of brittleness is wide and general problem for many intermetallics, superalloys and structural alloys. Based on knowledge from the bulk metallic glasses, their exceptional ductility in supercooled liquid state (several hundreds percent of macroscopic deformation) can be used for processing of potentially brittle materials which will exhibit definite functional properties, i.e., shape memory, after crystallization. Recently, the partners have got experience in the development of an effective AB-type, and potentially A3B- and AB3- type intermetallic alloys of specific compositions with relatively large glass forming ability in the bulk metallic precursor state by means of non-equilibrium processes including rapid solidification techniques (planar flow casting, twin roll casting, injection casting). Superplastic deformation of the material on heating from the glassy state through the supercooled liquid region or improved plastic property of alloys with small grains have been detected on melt-spun ribbons up to hundreds percents. Another technique in which the partners are experienced is the production of fine powders by electric spark erosion with typical powder particle size between 10 nm and 10 mm. Small additions of other specific elements may catalyze formation of amorphous phase. Ultrasonic assisted severe plastic deformation by ball milling for production of powders in nanocrystalline and amorphous states is available in IMP NASU.

Areas of Application

Grain size controlled shape memory alloys with high transformation temperature have high potential for use in automotive and air-space industries in which enhanced mechanical and functional properties are required. Natural refinement of the parent phase microstructure (formation of a microcrystalline structure with small mean grain size dispersion) helps to improve the mechanical properties (to increase strength) and thus fulfill the requirement of thermoelastic phase equilibrium, superelasticity and shape memory accompanying martensitic transformations at increased temperatures.

Today, SMA actuators are widely used to find potential solutions to practical problems involving smart structures. Smart structures use actuators to achieve a certain goal in commercial applications as valves, relays, safety devices, linear motors for reasons of weight, size, cost, noiselessness, simplicity.



Stage of Development

STCU and PICS projects designs are defended by publications in the international scientific journals.

Contact Details

Dr. Victor Kolomytsev
G.V.Kurdyumov Institute for Metal Physics, National Academy of Sciences of the Ukraine;
Kiev-142, 36, Vernadskogo Blvd.,
Tel/Fax: (380-44) 424-25-61
Mob.: 8(067) 506-37-67
E-mail: This e-mail address is being protected from spambots. You need JavaScript enabled to view it

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