Joining of parts via magnetic heating of metal-aluminum powders
A method of joining at least two parts includes steps of dispersing a joining material comprising a multi-phase nanocrystalline magnetic metal-aluminum powder at an interface between the at least two parts to be joined and applying an alternating magnetic field (AMF). The AMF has a magnetic field strength and frequency suitable for inducing magnetic hysteresis losses in the metal-aluminum powder and is applied for a period that raises temperature of the metal-aluminum powder to an exothermic transformation temperature. At the exothermic transformation temperature, the metal-aluminum powder melts and resolidifies as a metal aluminide solid having a non-magnetic configuration.
1. A method for joining at least two parts, said method comprising:
dispersing a joining material comprising a nanocrystalline metal-aluminum powder at an interface between at least two parts to be joined; and
applying an alternating magnetic field (AMF) having a magnetic field strength and frequency thereby inducing magnetic hysteresis losses in the metal-aluminum powder for a period that raises a temperature of the metal-aluminum powder to an exothermic transformation temperature where the metal-aluminum powder melts and resolidifies as a metal aluminide solid having a non-magnetic configuration.
2. The method of claim 1 , the joining material further comprising a solder.
3. The method of claim 1 , the joining material disposed within a polymer.
4. The method of claim 1 , the joining material disposed within a slurry.
5. The method of claim 1 , the AMF having a magnetic field strength in a range between 50 Oe and 2000 Oe.
6. The method of claim 1 , the AMF having a frequency in a range between 25 KHz and 100 MHz.
7. The method of claim 1 , wherein the period is in a range between 5 seconds and 100 seconds.
8. The method of claim 1 , wherein the at least two parts are joined at a non-planar interface.
9. The method of claim 1 , wherein the non-magnetic configuration of the metal aluminide is a B2 structure.
10. The method of claim 1 , wherein the metal aluminide is according to a formula:
(x)M-(y)Al,
wherein M is a metal or combination of metals selected from Fe, Ni and Co;
x ranges from 55 to 80 atomic percent; and
y ranges from 20 to 45 atomic percent.
11. The method of claim 10 , wherein x is 60 atomic percent and y is 40 atomic percent.
12. The method of claim 1 , wherein the metal aluminide is selected from the group consisting of iron aluminide, nickel aluminide, cobalt aluminide, ternary intermetallic compounds comprising Al and two metals selected from Fe, Ni and Co, quaternary intermetallic compounds comprising Fe, Ni, Co and Al, and physical mixtures thereof.
13. The method of claim 1 , wherein the metal aluminide is iron aluminide.
14. The method of claim 13 , wherein the iron aluminide comprises 60 atomic percent iron and 40 atomic percent aluminum.
15. The method of claim 1 , wherein the at least two parts form a combination selected from polymer-polymer, semiconductor-semiconductor, ceramic-ceramic, polymer-metal, polymer-semiconductor, polymer-ceramic, metal-semiconductor, metal-ceramic and semiconductor-ceramic.
16. The method of claim 1 , wherein the at least two parts form a combination selected from semiconductor-semiconductor, ceramic-ceramic, metal-semiconductor, metal-ceramic and semiconductor-ceramic.
17. The method of claim 1 , wherein the at least two parts form a combination selected from ceramic-ceramic and metal-ceramic.
18. The method of claim 1 , wherein particles of the nanocrystalline metal-aluminum powder have diameters of between 1 μm and 25 μm.
19. The method of claim 1 , wherein particles of the nanocrystalline metal-aluminum powder have diameters between 5 μm and 10 μm.
20. The method of claim 1 , wherein the step of dispersing comprises painting, silk screening or dipping.