Method for producing a monocrystalline body from a magnetic shape memory alloy

Abstract

A method for producing an MSM actuator element, having a crystal orientation along a first crystal axis, from a monocrystalline MSM body by introducing a molten alloying material into a molding shell and subsequently solidifying the alloying material, comprising the following steps: providing a molding shell which comprises a nucleation region ( 24 ), a selector region ( 26 ) and a crystal region ( 28 ) and is oriented along a longitudinal axis ( 22 ) at least in some sections, introducing the molten MSM alloying material, in particular NiMnGa-based alloying material, into the molding shell without providing a separate nucleation crystal, compacting the MSM alloying material by generating a solidification front moving from the nucleation region across the selector region into the crystal region along a solidification path.

1 - 12 . (canceled) 
     
     
         13 . A method for producing an MSM actuator element, having a determined crystal orientation along a first crystal axis, from a monocrystal MSM body by introducing a molten alloying material into a molding shell and subsequent solidification of the alloying material, comprising the steps of:
 (a) providing a molding shell which comprises a nucleation region, a selector region and a crystal region having a first crystal axis oriented in the direction of a longitudinal axis at least in some sections;   (b) introducing a molten MSM alloying material into the molding shell without providing a separate nucleation crystal;   (c) compacting the MSM alloying material by generating a solidification front moving from the nucleation region across the selector region into the crystal region along a solidification path, wherein the solidification path in the crystal region runs along the longitudinal axis, forms a region which is deflected from the longitudinal axis in the selector region, the maximum deflection of which, relative to the longitudinal axis, is greater than a maximum cross-sectional width in the selector region, wherein the longitudinal axis has an angular deviation of less than 10° from the first crystal axis; and   (d) dividing the solidified MSM alloying material into a plurality of MSM actuator elements by cuts perpendicularly to the longitudinal axis.   
     
     
         14 . The method according to  claim 13 , wherein the solidification path in the selector region forms a region which is deflected in a spike-like manner with two angled sections, the entry and exit side of which is aligned in alignment to the longitudinal axis. 
     
     
         15 . The method according to  claim 13 , wherein the solidification path in the selector region forms a helix-shaped or zigzag-shaped region. 
     
     
         16 . The method according to  claim 13 , wherein the longitudinal axis is aligned vertically to a flat cooling device associated with the nucleation region. 
     
     
         17 . The method according to  claim 13 , wherein the crystal region extending in an elongated manner along the longitudinal axis has an effective cross-sectional area for the solidification front of >3 cm 2 . 
     
     
         18 . The method according to  claim 13 , wherein the crystal region extending in an elongated manner along the longitudinal axis has an effective cross-sectional area for the solidification front of >7 cm 2 . 
     
     
         19 . The method according to  claim 13 , wherein the crystal region extending in an elongated manner along the longitudinal axis has an effective cross-sectional area for the solidification front of >12 cm 2 . 
     
     
         20 . The method according to  claim 13 , wherein the MSM alloying material for producing the solidification front is cooled so that a temperature gradient in the melt, occurring in the selector region, adjacent to the solidification front, is between 0.3 K/mm and 20 K/mm. 
     
     
         21 . The method according to  claim 13 , wherein the MSM alloying material for producing the solidification front is cooled so that a temperature gradient in the melt, occurring in the selector region, adjacent to the solidification front, is between 1 K/mm and 15 K/mm. 
     
     
         22 . The method according to  claim 13 , wherein the MSM alloying material for producing the solidification front is treated by bringing about a relative speed between the molding shell and the temperature gradient, so that the solidification front in the selector region moves at a speed of between 0.1 mm/min and 50 mm/min along the solidification path. 
     
     
         23 . The method according to  claim 13 , wherein the MSM alloying material for producing the solidification front is treated by bringing about a relative speed between the molding shell and the temperature gradient, so that the solidification front in the selector region moves at a speed of between 0.3 mm/min and 5 mm/min along the solidification path. 
     
     
         24 . The method according to  claim 13 , wherein the solidification front moves along the solidification path through an at least partially cross-sectionally rectangular crystal region. 
     
     
         25 . The method according to  claim 24 , wherein a cross-sectionally rectangular inner contour of the crystal region determines a crystal orientation of the MSM alloying material, which is solidified in a monocrystalline manner, in at least a second crystal axis orthogonal to the first crystal axis. 
     
     
         26 . The method according to  claim 13 , wherein the alloying material has Ni, Mn, Ga and at least Co in the composition Ni a Mn b Ga c Co d Fe e Cu f , wherein a, b, c, d, e and f are indicated in atom-% and fulfill the conditions
   44≦a≦51;
     19≦b≦30;
     18≦c≦24;
     0.1≦d≦15;
     0≦e≦14.9;
     0≦f≦14.9;
       d+e+f≦ 15;       a+b+c+d+e+f= 100.   
     
     
         27 . The method according to  claim 13 , wherein the compacting of the MSM alloying material takes place along a plurality of solidification paths which are adjacent to one another and separated from one another. 
     
     
         28 . The method according to  claim 13 , including dividing of the MSM alloying material, which is solidified in the crystal region, into the plurality of MSM actuator elements without previous metrological determining of a crystal orientation in the solidified MSM alloying material. 
     
     
         29 . The method according to  claim 13 , wherein the alloying material is NiMnGa.