Amorphous alloy composition for a magnetomechanical resonator and eas marker containing same

Abstract

The invention may include a novel composition for and/or processing of an active element for an EAS marker that achieves the same or better performance of existing materials while solving the problem of higher cost. It may include a magnetomechanical active element formed by planar strip of amorphous magnetostrictive alloy having a composition Fe a Ni b M c wherein a+b+c=100, wherein a is in a range of 40-70 weight percent, b is in a range of 10-50 weight percent, and c is in a range of 10-50 weight percent, and where M is the balance of remaining elements; wherein the magnetomechanical active element is subject to batch annealing in the presence of a magnetic field that is substantially transverse to the ribbon length of the element and at a temperature of less than about 300° C. and for a time greater than at least about one hour.

1 . A marker for use in a magnetomechanical electronic article surveillance (EAS) system comprising:
 a magnetomechanical active element formed by planar strip of amorphous magnetostrictive alloy having a composition Fe a Ni b M c  wherein a+b+c=100, wherein a is in a range of 40-70 weight percent, b is in a range of 10-50 weight percent, and c is in a range of 10-50 weight percent, and where M is the balance of remaining elements;   a biasing element located adjacent said resonator element;   a housing configured to contain said resonator element and said biasing element; and   wherein said magnetomechanical active element is subject to batch annealing in the presence of a magnetic field that is substantially transverse to the plane of said element and at a temperature of less than about 300° C. at a temperature of greater than at least about one hour.   
     
     
         2 . The marker of  claim 1 , wherein M is one or more selected from the group consisting of Co, Si, B, C, P, Sn, Cu, Ge, Nb, Mo, Cr and Mn. 
     
     
         3 . The marker of  claim 1 , wherein M comprises one or more selected from the group consisting of Si, B, C, and P. 
     
     
         4 . The marker of  claim 3 , wherein M is from about 15 to about 30 weight percent. 
     
     
         5 . The marker of  claim 1 , wherein M comprises one or more selected from the group consisting of Sn, Cu, Ge, Nb, Mo, Cr, Mn, and Mismetal. 
     
     
         6 . The marker of  claim 5 , wherein M is from about 0 to about 10 weight percent. 
     
     
         7 . The marker of  claim 1 , wherein M comprises one or more first elements selected from the group consisting of Si, B, C, and P to affect the glassy nature of said active element; and one or more second elements selected from the group consisting of Sn, Cu, Ge, Nb, Mo, Cr, Mn and Mismetal to affect the magnetic properties of said active element. 
     
     
         8 . The marker of  claim 7 , wherein said first element comprises about 15 to about 30 weight percent of said active element, and said second element comprises about 0 to about 10 weight percent of said active element. 
     
     
         9 . The marker of  claim 1 , wherein the amount of Ni, b, is less than about 25 weight percent. 
     
     
         10 . The marker of  claim 1 , wherein said batch annealing is conducted at a temperature of about 250° C. for about one hour.