RAPID SOLIDIFIED DUCTILE Cu-Al-Mn RIBBON FOR ELASTOCALORIC APPLICATIONS

Abstract

A ribbon of elastocaloric material is provided. The ribbon is made from copper alloyed with aluminum and manganese. The ribbon has a length, a width, and a thickness. The length is a longest dimension of the ribbon, and the width is perpendicular to the length. The thickness is perpendicular to both the length and the width, and the thickness is 0.1 mm or less. Further, in a room temperature ambient environment, the ribbon increases in temperature by at least 4° C. upon application of 6% of tensile strain and cools by at least 4° C. when the tensile strain is unloaded.

What is claimed is: 
     
         1 . A ribbon of elastocaloric material, comprising:
 copper alloyed with aluminum and manganese;   wherein the ribbon comprises a length, a width, and a thickness, the length being a longest dimension of the ribbon, the width being perpendicular to the length, and the thickness being perpendicular to both the length and the width, the thickness being 0.1 mm or less; and   wherein, in a room temperature ambient environment, the ribbon increases in temperature by at least 4° C. upon application of 6% of tensile strain and cools by at least 4° C. when the tensile strain is unloaded.   
     
     
         2 . The ribbon of elastocaloric material of  claim 1 , wherein a microstructure of the ribbon is oligocrystalline comprising columnar grains extending across a thickness of the ribbon separated by intergrain nodes and wherein the columnar grains each comprise a width, the width being at least twice the thickness. 
     
     
         3 . The ribbon of elastocaloric material of  claim 2 , wherein the ribbon exhibits an induced magnetic moment of at least 1 emu/g in an applied magnetic field of ±30 kOe. 
     
     
         4 . The ribbon of elastocaloric material of  claim 2 , wherein the ribbon exhibits a latent heat of martensitic transformation of at least 5.0 J/g. 
     
     
         5 . The ribbon of elastocaloric material of  claim 2 , comprising an elastic modulus of at least 10 GPa. 
     
     
         6 . The ribbon of elastocaloric material of  claim 2 , comprising a yield strength (σ 0.2 ) of at least 50 MPa. 
     
     
         7 . The ribbon of elastocaloric material of  claim 2 , comprising a critical transformation stress of at least 50 MPa. 
     
     
         8 . The ribbon of elastocaloric material of  claim 2 , comprising an ultimate tensile strength of at least 200 MPa. 
     
     
         9 . The ribbon of elastocaloric material of  claim 2 , comprising a total strain before failure of at least 5%. 
     
     
         10 . The ribbon of elastocaloric material of  claim 1 , wherein a microstructure of the ribbon comprises columnar grains extending across a thickness of the ribbon and wherein the columnar grains each comprise a width, the width being more than the thickness. 
     
     
         11 . The ribbon of elastocaloric material of  claim 1 , wherein the copper alloyed with aluminum and manganese comprises a formula of Cu 72 Al x Mn y , where x=17±5, and y=11±5. 
     
     
         12 . The ribbon of elastocaloric material of  claim 1 , wherein the copper alloyed with aluminum and manganese further comprises up to 5 at % of a metal selected from a group consisting of Ni, Ag, Au, Zn, Sn, Ti, Cr, Fe, Co, Si, and combinations thereof. 
     
     
         13 . A cloth comprising at least one ribbon of elastocaloric material according to  claim 1 . 
     
     
         14 . A method of preparing a ribbon elastocaloric material, the method comprising:
 directing a stream of the elastocaloric material in a molten form onto an outer surface of a rotating wheel, the elastocaloric material comprising copper alloyed with aluminum and manganese;   cooling the stream of elastocaloric material on the outer surface of the rotating wheel to form the ribbon; and   removing the ribbon from the outer surface of the rotating wheel;   wherein the ribbon comprises a thickness as measured perpendicular to the outer surface, the thickness being 0.1 mm or less.   
     
     
         15 . The method of  claim 14 , further comprising annealing the ribbon at a temperature in a range from 600° C. to 1100° C. for a time in a range from 5 minutes to 10 hours. 
     
     
         16 . The method of  claim 14 , further comprising aging the ribbon at a temperature in a range from 50° C. to 500° C. for a time in a range from 1 minutes to 2 hours. 
     
     
         17 . The method of  claim 16 , wherein, after aging, the ribbon comprises an oligocrystalline microstructure having columnar grains extending across the thickness of the ribbon, wherein the columnar grains are separated by intergrain nodes and wherein the columnar grains each comprise a grain width, the grain width being at least twice the thickness. 
     
     
         18 . The method of  claim 16 , wherein the ribbon exhibits an induced magnetic moment of at least 1 emu/g in an applied magnetic field of ±30 kOe. 
     
     
         19 . The method of  claim 16 , wherein the ribbon exhibits a latent heat of martensitic transformation of at least 5.0 J/g. 
     
     
         20 . The method of  claim 16 , wherein the ribbon comprises an elastic modulus of at least 10 GPa. 
     
     
         21 . The method of  claim 16 , wherein the ribbon comprises a yield strength (σ 0.2 ) of at least 50 MPa. 
     
     
         22 . The method of  claim 16 , wherein the ribbon comprises a critical transformation stress of at least 50 MPa. 
     
     
         23 . The method of  claim 16 , wherein the ribbon comprises an ultimate tensile strength of at least 200 MPa. 
     
     
         24 . The method of  claim 16 , wherein the ribbon comprises a total strain before failure of at least 5%. 
     
     
         25 . The method of  claim 14 , wherein the copper alloyed with aluminum and manganese comprises a formula of Cu 72 Al x Mn y , where x=17±5, and y=11±5. 
     
     
         26 . The method of  claim 14 , wherein the copper alloyed with aluminum and manganese further comprises up to 5 at % of a metal selected from a group consisting of Ni, Ag, Au, Zn, Sn, Ti, Cr, Fe, Co, Si, and combinations thereof.