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Aluminum filler metals are used to braze aluminum base metals using various methods, the most common being salt dip bath, vacuum, and flux (either torch or furnace). Aluminum brazing requires tighter process parameters than most brazing processes because of the close relationship between the melting point of the braze filler metal and the base metal. Cleanliness is very important when brazing aluminum base metals. All oil, scale or heavy oxides from extrusion or rolling process must be removed prior to brazing. (Note: It is impossible to remove all oxides from aluminum due to its natural affinity to oxidize upon exposure to air.) Filler metals for brazing aluminum are available in wire, powder and paste, foil and as clad sheet. Not all filler metals are available in all forms. Some may be very difficult to locate in small quantities domestically, if at all. Aluminum filler metals are also sometimes used to braze titanium alloys.
| Filler Metal | AWS A5.8 | AMS | Solidus °F/°C | Liquidus °F/°C | Remarks |
| AL716 | BAISi3 | 4184 | 970/521 | 1085/585 | Available in wire and preforms. Wide melting range (less Fluid) filler metal. |
| AL718 | BAISi4 | 4185 | 1070/577 | 1080/582 | Available in strip, wire, powder, paste and preforms. Most fluid of the aluminum filler metals. |
| AL719 | 960/516 | 1040/560 | Available as a powder or paste. | ||
| AL802 | 710/377 | 725/385 | Available as wire and preforms. High temperature solder for aluminum. |
Solders are low melting filler metals that are set to join a wide variety of materials. Solders melt below 840°F (450°C), and so can only be used for low temperature applications. The process is generally preformed using a torch, iron, or using furnace, wave or ultrasonic methods. Soldering generally requires a flux. Fluxes for soldering range from being non corrosive to being very corrosive. Flux selection is based on the materials to be soldered and the melting temperature of the base metal. Solder selection is dependent upon the base metals, corrosion resistance required, service temperature, and required strength and creep properties. These are just some of the more common solders that Lucas-Milhaupt offers. Call our customer service department for information on other alloys available.
| Filler Metal | Solidus °F/°C | Liquidus °F/°C | Comments |
| 96.5Sn/3.5Ag | 430/221 | 430/221 | Eutectic alloy. Wets Cu, Brass, Steel, SS. |
| 95 Sn/5 Sb | 452/233 | 464/240 | For Cu to Cu. Good creep strength. Not for brass. |
| 63 Sn/37 Pb | 361/183 | 361/183 | Eutectic-highest strength of Tin/Lead alloy series. |
| 60 Sn/40 Pb | 361/183 | 374/190 | Electronic solder. |
| 50 Sn/50 Pb | 361/183 | 421/216 | Good general purpose alloy. Use either rosin or acid flux. |
| 40 Sn/60 Pb | 361/183 | 460/238 | Good for preforms. Use acid flux. |
| 95 Cd/5 Ag (BR 053 TEC) | 640/338 | 740/393 | Hi-Temp. solder-good strength. |
| 80 Au/20Sn | 536/280 | 536/280 | Low ductility alloy. Low vapor pressure alloy. |
| 78.4 Cd/16.6 Zn/5 Ag (Br 056) | 480/249 | 600/316 | Hi-Temp. solder-good strength. |
| 97.5 Pb/2.5 Ag | 579/304 | 579/304 | Eutectic alloy-a homogenous alloy. |
| 97.5 Pb/1.5 Ag/1 Sn | 588/309 | 588/309 | Good corrosion resistance in humid atmospheres. |
Forms available: Most solders are available in powder, paste, wire, and strip forms. Some solders, such as the Au/Sn, are brittle in nature and are not available in some forms.
Gold based filler metals are used to join steels, stainless steels, nickel based alloys and other materials, where ductility and resistance to oxidation or corrosion is necessary. Gold filler metals readily wet most base metals, including the super alloys, and are especially good for brazing thin sections due to their low interaction with the base metal. Most gold based brazing filler metals are rated for continuous service up to 800°F (425°C). Those containing nickel may be used at higher temperatures.
| Filler Metal | AWS A5.8 Classification | AMS | Solidus °F/°C | Liquidus °F/°C | Comments |
| Premabraze 920 | BVAu-8 Gr 1 | 2190/1199 | 2265/1241 | Oxidation resistant, ductile For Mo, W, Ta & Super alloys | |
| 82 Au/18 Ni | BAu-4 | 4787 | 1740/949 | 1740/949 | For SS, Inconnel, KovarŪ, etc. oxidation resistance to 1500°F (816°C) |
| LM 131 Gr 1 | BVAu-4 Gr 1 | 740/949 | 1740/949 | For SS, Inconnel, KovarŪ, etc. oxidation resistance to 1500°F (816°C) for vacuum application | |
| 81.5 Au/16.5 Cu/2 Ni | 1670/910 | 1670/910 | For Cu, Ni, Mo/Mn. Remains ductile. | ||
| 80 Au/20 Cu | BVAu2 Gr1 | 1635/891 | 1635/891 | Lowest melting of Cu-Au alloys. Loses ductility above 200°F (96°C). | |
| 75 Au/20 Cu/5 Au | 1625/885 | 1643/895 | Narrow melting rang. Good for step-brazing. | ||
| 70 Au/8 Pd/22 Ni | BAu-6 | 4786 | 1845/1007 | 1915/1046 | For Super alloys and Ss. High ductility and strength. |
| 60 Au/37 Cu/3 Ni | 1580/860 | 1652/900 | Lower braze temperature than Cu-Au series. | ||
| 60 Au/20 Cu/20 Ag | 1535/835 | 1553/845 | Narrow melting range. Useful for step-brazing | ||
| 50 Au/ 50Cu | 1735/955 | 1778/970 | For Cu, Ni, KovarŪ & Mo/Mn metallized ceramic. | ||
| Premabraze 500 | BVAu-7 Gr 1 | 4784 | 2015/1102 | 2050/1121 | High strength & oxidation resistance. Brazing Super alloys. |
| 40 Au/60 Cu | 1796/980 | 1832/1000 | For Cu, Ni, KovarŪ & Mo/Mn metallized ceramic. | ||
| 37.5 Au/62.5 Cu | BAu-1 | 1815/991 | 1860/1016 | For Cu, Ni, KovarŪ & Mo/Mn metallized ceramic. | |
| 35 Au/65 Cu | 1814/990 | 1850/1010 | For Cu, Ni, KovarŪ & Mo/Mn metallized ceramic. | ||
| 35 Au/62 Cu/3 Ni | BAu-3 | 1785/974 | 1885/1029 | Good for Ni, Mo, SS, KovarŪ and Mo/Mn-low penetration. | |
| 30 Au/34 Pd/ 36 Ni | BAu-5 | 4785 | 2075/1135 | 2130/1166 | High strength-good oxidation resis.--For Super alloys. |
KovarŪ is a registered trademark of CSR Holdings, Inc., a subsidiary of Carpenter Technology Corporation.
Forms available: Gold based filler metals are available in wire strip, powder, paste and preformed shapes. While generally available, inventory levels may be limited due to the high precious metal content. Please check with your customer service representative for specific delivery.
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