Hydrogen storage metal alloy and production thereof

Abstract

A process for producing hydrogen storage metal alloys having a body-centered cubic structure-type main phase enabling the adsorption and desorption of hydrogen is provided which comprises the steps of: (1) melting a starting alloy brought to a predetermined element ratio to form a uniform heat (melting step), (2) keeping the homogenized alloy heat at a temperature within a range just below the melting point of the alloy for a predetermined time (heat treatment), and (3) rapidly cooling the alloy after the heat treatment (quenching step).

1 - 12 . (canceled)  
     
     
         13 . A process for producing a hydrogen storage metal alloy having a main phase with body-centered cubic structure wherein the body-centered cubic structure phase enables adsorption and desorption of hydrogen, comprising the steps of: 
 (1) providing a starting mixture which has a composition of the following general composition formula:      Ti (100-a-0.4b) Cr (a-0.6b) M b   (i)    wherein M is vanadium (V), provided that 20≦a (at %)≦80, and 0<b (at %)<10; or      Ti (100-a-0.4b) Cr (a-0.6b) M b   (ii)    wherein M is at least a member selected from molybdenum (Mo) and tungsten (W), wherein 20≦a (at %)≦80, 0<b (at %)<5, and when M is W said metal alloy has a hydrogen storage capacity of at least 2.6 mass % or more; or      Ti (100-a-0.4b) Cr (a-0.6b) V (b-c) M c   (iii)    wherein M is at least a member selected from molybdenum (Mo) and tungsten (W), wherein 20≦a (at %)≦80, 0<b (at %)≦10, and 0<c (at %)<5; or      Ti (100-a) Cra  (iv)    wherein 20≦a (at %)≦80;    (2) repeatedly melting and solidifying the starting mixture to form a heated homogeneous alloy;    (3) maintaining the heated homogeneous alloy at a temperature of at least 1400° C. within a range just below the melting point of the alloy for a predetermined time of from 1 minute to 2 hours; and    (4) rapidly cooling the alloy from step (3) in iced water.    
     
     
         14 . The process of  claim 13 , wherein said melting and solidifying are carried out repeatedly for predetermined times in step (2).  
     
     
         15 . The process of  claim 13 , wherein the starting mixture contains an additional element X admixed at its atom % concentration, d (at %), ranging within 0≦d (at %)≦20 and includes at least one or more other elements selected from the group consisting of Al, Ge, Ga, Si, Au and Pt.  
     
     
         16 . The process of  claim 13 , wherein the starting mixture contains an additional element T admixed at its atom % concentration, e (at %), ranging within 0≦e (at %)≦10 and includes at least one or more other elements selected from the group consisting of Nb, Ta, Mn, Fe, Al, B, C, Co, Cu, Ga, Ge, a lanthanoid metal, N, Ni, P, and Si.  
     
     
         17 . The process of  claim 15 , wherein the starting mixture contains an additional element T admixed at its atom % concentration, e (at %), ranging within 0≦e (at %)≦10 and includes at least one or more other elements selected from the group consisting of Nb, Ta, Mn, Fe, Al, B, C, Co, Cu, Ga, Ge, a lanthanoid metal, N, Ni, P, and Si.  
     
     
         18 . The process of  claim 13 , wherein the starting mixture has a composition of the following general composition formula:  
         Ti (100-a-0.4b) Cr (a-0.6b) M b    
       wherein M is vanadium (V), provided that 20≦a (at %)≦80, and 0<b (at %)<10.  
     
     
         19 . The process of  claim 18 , wherein a level of the constituent element V contained in the mixture is within a range of 6±2 at %.  
     
     
         20 . The process of  claim 13 , wherein the starting mixture has a composition of the following general composition formula:  
         Ti (100-a-0.4b) Cr (a-0.6b) M b    
       wherein M is at least a member selected from molybdenum (Mo) and tungsten (W), wherein 20≦a (at %)≦80, 0<b (at %)<5, and when M is W said resulting metal alloy has the hydrogen storage capacity of at least 2.6 mass % or more.  
     
     
         21 . The process of  claim 20 , wherein a level each of the constituent element Mo and/or W contained in the starting mixture is within a range of 3±1.5 at %.  
     
     
         22 . The process of  claim 13 , wherein in step (3) the alloy is kept at the temperature of at least 1400° C. or higher and just below the melting point of the alloy.  
     
     
         23 . The process of  claim 13 , wherein the predetermined time range in step (3) is from 1 minute to 1.9 hours.  
     
     
         24 . The process of  claim 13 , wherein the predetermined time range in step (3) is from 1 minute to 100 minutes.  
     
     
         25 . The process of  claim 13 , wherein the predetermined time range in step (3) is from 1 minute to 1 hour.