Molybdenum alloy x-ray targets having uniform grain structure

Abstract

The invention relates to a process for making a cross-directionally worked molybdenum plate, the process comprising: (a) reducing ammonium molybdate and forming molybdenum metal powder; (b) consolidating a molybdenum component comprised of molybdenum metal powder and an alloying element to a first workpiece, the alloying element being selected from the group consisting of titanium, zirconium, hafnium, carbon, lanthanum oxide, and combinations thereof; (c) thermally treating the first workpiece and subjecting the workpiece to thermo-mechanical forces in a first direction, and thereby forming a second workpiece; (d) thermally treating the second workpiece and subjecting the second workpiece to thermo-mechanical forces in a second direction that is different from the first direction; (e) subjecting the thermomechanically treated second workpiece to a recrystallization heat treatment step, and thereby forming a heat-treated crossdirectionally worked workpiece; and (f) subjecting the heat-treated, cross-directionally worked workpiece to a slicing step or a machining step, and thereby forming the cross-directionally worked molybdenum plate. The invention also relates to X-ray targets made from the process.

1 . A process for making a cross-directionally worked molybdenum plate, the process comprising: 
 (a) reducing ammonium molybdate and forming molybdenum metal powder;    (b) consolidating a molybdenum component comprised of molybdenum metal powder and an alloying element to a first workpiece, the alloying element being selected from the group consisting of titanium, zirconium, hafnium, carbon, lanthanum oxide, and combinations thereof;    (c) thermally treating the first workpiece and subjecting the workpiece to thermo-mechanical forces in a first direction, and thereby forming a second workpiece;    (d) thermally treating the second workpiece and subjecting the second workpiece to thermo-mechanical forces in a second direction that is different from the first direction;    (e) subjecting the thermomechanically treated second workpiece to a recrystallization heat treatment step, and thereby forming a heat-treated crossdirectionally worked workpiece; and    (f) subjecting the heat-treated, cross-directionally worked workpiece to a slicing step or a machining step, and thereby forming the cross-directionally worked molybdenum plate.    
     
     
         2 . The process of  claim 1 , wherein the first workpiece further comprises niobium in an amount that is less than about 3 wt. %.  
     
     
         3 . The process of  claim 1 , wherein the first workpiece further comprises tungsten in an amount ranging from about 1 to about 30 wt. %.  
     
     
         4 . The process of  claim 1 , wherein the molybdenum component is consolidated into the first workpiece by a powder metallurgical technique.  
     
     
         5 . The process of  claim 1 , wherein the molybdenum component is consolidated into the first workpiece by an arc casting technique.  
     
     
         6 . The process of  claim 5 , wherein the arc casting technique is a vacuum arc casting technique.  
     
     
         7 . The process of  claim 1 , wherein the first workpiece is a billet or an ingot and the first workpiece is thermo-mechanically treated by extruding the billet or the ingot to a ratio of reduction (D o :D f ) in a cross-sectional area ranging from about 3:1 through about 4:1.  
     
     
         8 . The process of  claim 1 , wherein in step (d), the second workpiece is subjected to upset forging.  
     
     
         9 . The process of  claim 8 , wherein second workpiece is upset forged by a closed die forging process with a closed die that is dimensioned to form a plate.  
     
     
         10 . The process of  claim 8 , wherein second workpiece is upset forged by an open die forging process with an open die that is dimensioned to form a plate.  
     
     
         11 . The process of  claim 9 , wherein in step (d), the closed die is further dimensioned to include a mold for a stem so that the plate formed by the process in step (e) further comprises a stem.  
     
     
         12 . A member made by the process of  claim 11 , wherein the member comprises a plate and a stem attached to the plate.  
     
     
         13 . A plate made from the process of  claim 1 , wherein the plate is a cross-directionally worked plate having a uniform grain structure.  
     
     
         14 . The process of  claim 1 , wherein the alloying element is present in an amount that is about 1.2 wt. %, or less.  
     
     
         15 . The process of  claim 1 , wherein the alloying element is present in an amount ranging from about 1 wt. % to about 1.5 wt. %.  
     
     
         16 . The process of  claim 1 , wherein the plate has a diameter ranging from about 1″ to about 14″ and a thickness/height ranging from about ¼″ to about 7″.  
     
     
         17 . The process of  claim 1 , wherein the plate made by the process has a radial strength of at least about 60 ksi when the plate is exposed to a temperature of about 1600° C.  
     
     
         18 . The process of  claim 1 , wherein the alloying element comprises lanthanum oxide, and the plate made by the process has improved creep resistance, as compared to a plate made without lanthanum oxide.  
     
     
         19 . A plate comprising a cross-directionally worked molybdenum component selected from the group consisting of (i) a molybdenum component containing molybdenum and an alloying element selected from the group consisting of titanium, zirconium, hafnium, carbon, lanthanum oxide, and combinations thereof or (ii) a molybdenum component comprising molybdenum, niobium and an alloying element selected from the group consisting of titanium, zirconium, hafnium, carbon, lanthanum oxide, and combinations thereof or (iii) a molybdenum component comprising molybdenum, tungsten in an amount ranging from about 1 to about 30 wt. % and an alloying element selected from the group consisting of titanium, zirconium, hafnium, carbon, lanthanum oxide, and combinations thereof; 
 wherein the plate has a radial strength of at least about 60 ksi when the plate is exposed to a temperature of about 1600° C.    
     
     
         20 . The plate of  claim 19 , wherein the plate further comprises a stem.  
     
     
         21 . An X-ray target comprising: 
 (a) a plate comprising a cross-directionally worked molybdenum component selected from the group consisting of (i) a molybdenum component containing molybdenum and an alloying element selected from the group consisting of titanium, zirconium, hafnium, carbon, lanthanum oxide, and combinations thereof or (ii) a molybdenum component comprising molybdenum, niobium and an alloying-element selected from the group consisting of titanium, zirconium, hafnium, carbon, lanthanum oxide, and combinations thereof or (iii) a molybdenum component comprising molybdenum, tungsten in an amount ranging from about 1 to about 30 wt. % and an alloying element selected from the group consisting of titanium, zirconium, hafnium, carbon, lanthanum oxide, and combinations thereof;    wherein the plate has a radial strength of at least about 60 ksi when the plate is exposed to a temperature of about 1600° C.;    (b) a focal track located on a surface of the plate; and    (c) a stem extending from the plate.    
     
     
         22 . The target of  claim 21 , wherein the stem comprises a worked molybdenum component selected from the group consisting of (i) a molybdenum component containing molybdenum and an alloying element selected from the group consisting of titanium, zirconium, hafnium, carbon, lanthanum oxide, and combinations thereof or (ii) a molybdenum component comprising molybdenum, niobium and an alloying element selected from the group consisting of titanium, zirconium, hafnium, carbon, lanthanum oxide, and combinations thereof or (iii) a molybdenum component comprising molybdenum, tungsten in an amount ranging from about 1 to about 30 wt. % and an alloying element selected from the group consisting of titanium, zirconium, hafnium, carbon, lanthanum oxide, and combinations thereof, 
 wherein the stem also has a strength of at least about 60 ksi when the stem is exposed to a temperature of about 1600° C.