as indicated above , the alloys of the present invention include palladium as the principal component . varying amounts of gold , silver , platinum , gallium , indium , and tin are used to achieve the desired properties . furthermore , minor amounts of other elements may also be included in the alloys . the preferred embodiments of the present invention fall into three groups . the first embodiment includes an alloy consisting essentially of about 50 - 61 % palladium , 35 - 40 % gold , 0 . 5 - 2 . 5 % silver , 0 . 01 - 0 . 1 % rhenium , 0 . 01 - 0 . 1 % ruthenium , and varying combinations of 2 - 8 % gallium , 0 - 8 % indium , and 0 - 8 % tin . the various amounts of gallium , indium , and tin control the melting range , strength , and modulus of elasticity of the resultant alloy . basically , all three elements decrease the melting range and increase the strength of the alloy . their effects on modulus seem to be more synergistic . thus , various combinations of the three elements produce greater effects that the sum total of the effects of the elements individually . additionally , it is preferable to add silver to the alloy to increase the thermal expansion . without the silver , the alloy of this embodiment tends to have an expansion on the low side of average for porcelain - fused - to - metal alloys . by raising the expansion toward the middle of the range of alloy expansion , one broadens the range of porcelains with which the alloy will be compatible . also , the silver tends to increase the modulus in conjunction with indium . furthermore , rhenium and ruthenium provide for effective grain refining . alloys in this group can develop 0 . 1 % yield strengths over 130 , 000 psi and elastic moduli in excess of 25 , 000 , 000 psi . yield strength describes the stress at which the alloys or compound begins to function in a plastic manner ( craig , r ., restorative dental materials , 7th ed ., p . 73 ( c . v . mosby co . 1985 )). elastic modulus refers to the relative stiffness of the material with the range of elasticity ( craig , r ., supra at p . 79 ). with regard to the first embodiment of the invention , the alloy preferably consists essentially , by weight , of about 55 - 57 % palladium , 36 - 38 % gold , 1 - 2 % silver , 5 - 7 % gallium , 0 % indium , 0 % tin , 0 . 04 - 0 . 06 % rhenium and 0 . 04 - 0 . 06 % ruthenium . the alloy , more preferably consists essentially , by weight , of about 55 . 9 % palladium , 37 % gold , 1 % silver , 6 % gallium , 0 . 05 % rhenium and 0 . 05 % ruthenium ( see example one ). the second embodiment includes an alloy consisting essentially , by weight , of about 50 - 61 % palladium 25 - 37 % silver , 0 . 01 - 0 . 1 % rhenium and 0 . 01 - 0 . 1 % ruthenium with varying combinations of 1 . 8 - 3 % gold , 4 - 7 % tin , 0 . 5 - 3 % gallium , 0 . 5 - 3 % indium , and 0 - 2 % platinum . rhenium and ruthenium are used for grain refining . alloys in this group can develop 0 . 1 % yield strengths over 90 , 000 psi and elastic moduli in excess of 24 , 000 , 000 psi . the alloy of the second embodiment preferably consists essentially , by weight , of about 58 - 60 % palladium , 25 - 28 % silver , 2 - 3 % gold , 5 - 7 % tin , 1 - 2 % gallium , 1 - 2 % indium , 1 - 2 % platinum , 0 . 04 - 0 . 06 % rhenium and 0 . 04 - 0 . 06 % ruthenium . the alloy more preferably consists essentially , by weight , of about 59 . 9 % palladium , 26 % silver , 2 . 75 % gold , 7 % tin , 2 % gallium , 1 . 5 % indium , 1 . 0 % platinum , 0 . 05 % rhenium and 0 . 05 % ruthenium ( see example one ). the third embodiment includes an alloy consisting essentially of about 77 - 95 % palladium , 2 - 3 % gold , 2 - 3 % silver , 0 . 01 - 0 . 1 % rhenium and 0 . 01 - 0 . 1 % ruthenium with 0 - 6 % each of gallium , indium , and tin . as in the previous two groups , rhenium and ruthenium are used for grain refining . alloys in this group can develop 0 . 1 % yield strengths over 100 , 000 psi and elastic moduli in excess of 24 , 000 , 000 psi . the alloy of the third embodiment of the present invention preferably consists essentially , by weight , of about 80 - 82 % palladium , 2 . 3 - 2 - 7 % gold , 2 . 3 - 2 . 7 % silver , 4 - 6 % gallium , 2 - 5 % indium , 0 - 4 % tin , 0 . 05 - 0 . 1 % rhenium and 0 . 05 - 0 . 1 % ruthenium . the alloy more preferably consists essentially , by weight , of about 81 . 9 % palladium , 2 . 5 % gold , 2 . 5 % silver , 6 . 0 % gallium , 3 . 5 % indium , 0 . 1 % rhenium and 0 . 1 % ruthenium ( see example three ). gold alloys which could be used for the same purpose have yield strengths of 45 - 60 , 000 psi and moduli of 12 - 14 million psi . however , as can be observed based on these properties , the gold - based alloys are not strong or rigid enough to be used in high stress situations such as in long span bridges and cantilevered sections . presently known palladium alloys can also generate yield strengths in excess of 100 , 000 psi , but their moduli are in the range of 14 - 16 million psi . the increases in the moduli of the alloys of the present invention reduce the amount of distortion that occurs under load , and the high yield strengths provide protection against permanent deformation . with respect to modifications of the three embodiments set forth above , one could add copper and / or cobalt in place of some or all of the gallium , indium , and / or tin to make the alloys stronger . however , this addition or substitution would tend to make the oxide produced for bonding to porcelain darker in color , and possibly , less desirable . normally , the alloys discussed above are white in color . furthermore , it should be noted that all of the alloys of the present invention can be used in traditional dentistry as well as in implant dentistry . in particular , the alloys are suitable for manufacturing crowns and bridges with or without coverings of resin or porcelain materials . in addition , the alloys of the present invention could also be utilized for jewelry , as a less expensive alternative to white golds . the production of the alloys does not require any special steps other than those used in the traditional production of dental alloys . basically , the alloys are melted , usually by induction heating , at atmospheric pressure and usually under the flame of a reducing gas such as , for example , carbon monoxide or natural gas . vacuum melting is not utilized . ( if necessary , the alloys ( if hardened ) may be remelted either by induction or with a gas - oxygen torch with no additional protection .) the alloys are then cast into a ceramic mold of the desired shape under normal atmospheric condition . the present invention can be illustrated by the use of the following non - limiting examples . ______________________________________composition : ______________________________________pd 56 . 0 % au 37 . 0 % ag 1 . 0 % ga 6 . 0 % in --% sn --% plus grain refiners______________________________________physical & amp ; mechanical properties : porcelain hardened______________________________________yield strength ( 0 . 1 % offset ) 80 , 900 psiproof stress ( 0 . 2 % offset ) 580 mpvickers hardness 275elongation 35 % modulus of elasticity ( psi ) 18 , 400 , 000density ( g / cm . sup . 3 ) 13 . 0melting range 2110 - 2335 f . 1155 - 1280 c . casting temperature 2435 f . 1335 c . coefficient of thermal exp 14 . 3 × 10 . sup .- 6 /° c . heat treatmentnot heat hardenable______________________________________ this alloy was subjected to thermal shock testing with ceramco ii , crystar , duceram , vita , and will ceram porcelains . results pending ______________________________________additional data : ______________________________________annealing temperature 1500 f . weighted sag ( 1850 f ., 5 min ) 0 . 50 mmbutton test no porositygrain size 50 microns______________________________________ ______________________________________composition : ______________________________________pd 60 . 0 % au 3 . 0 % ag 26 . 0 % pt 1 . 0 % ga 2 . 0 % in 1 . 5 % sn 7 . 0 % plus grain refiners______________________________________physical & amp ; mechanical properties : porcelain hardened______________________________________yield strength ( 0 . 1 % offset ) 80 , 200 psi 87 , 300 psiproof stress ( 0 . 2 % offset ) 560 mp 615 mpavickers hardness 230 265elongation 31 % 28 . 5 % modulus of elasticity ( psi ) 18 , 000 , 000density ( g / cm . sup . 3 ) 11 . 2melting range 2110 - 2335 f . 1150 - 1280 c . casting temperature 2435 f . 1335 c . coefficient of thermal exp 14 . 9 × 10 . sup .- 6 /° c . ______________________________________ to harden : heat at 1100 ° f . ( 595 ) for 15 minutes , air cool this alloy was subjected to thermal shock testing with ceramco ii , crystar , duceram , vita , and will ceram porcelains . results pending ______________________________________additional data : ______________________________________annealing temperature 1750 f . weighted sag ( 1850 f ., 5 min ) 1 . 94 mmbutton test no porositygrain size 13 microns______________________________________ ______________________________________composition : ______________________________________pd 82 . 0 % au 2 . 5 % ag 2 . 5 % ga 6 . 0 % in 3 . 5 % sn 3 . 5 % plus grain refiners______________________________________physical & amp ; mechanical properties : porcelain hardened______________________________________yield strength ( 0 . 1 % offset ) 64 , 500 psi 67 , 500 psiproof stress ( 0 . 2 % offset ) 470 mp 485 mpavickers hardness 240 260elongation 41 % 37 % modulus of elasticity ( psi ) 21 , 500 , 000density ( g / cm . sup . 3 ) 11 . 4melting range 2130 - 2435 f . 1165 - 1335 c . casting temperature 2535 f . 1390 c . coefficient of thermal exp 14 . 1 × 10 . sup .- 6 /° c . ______________________________________ to harden : heat at 1200 ° f . ( 650 ° c .) for 30 minutes , air cool this alloy was subjected to thermal shock testing with ceramco ii , crystar , duceram , vita , and will ceram porcelains . the alloy performed well with all porcelains . note : no failures occurred until 170 ° c . ; after the maximum temperature of 200 ° c . there were still bridges of crystar , duceram , and will ceram without any cracks . after completion of the test none of the porcelains exhibited cracks at 100 % of the units . this is extremely unusual , and indicates an exceptionally high potential for porcelain compatibility . ______________________________________additional data : ______________________________________annealing temperature 1700 - 1600weighted sag ( 1850 f ., 5 min ) 0 . 74 mmbutton test no porositygrain size 30 microns______________________________________ ______________________________________constituents weightof alloys % properties of alloy______________________________________pd 54 . 9 0 . 1 % offset yield strength - 133 , 000 psiau 37 . 0 modulus of elasticity - 18 , 000 , 000 psiga 8 . 0re 0 . 05ru 0 . 05______________________________________ ______________________________________constituents weightof alloys % properties of alloy______________________________________pd 51 . 9 0 . 1 % offset yield strength - 133 , 000 psiau 37 . 0 modulus of elasticity - 18 , 000 , 000 psiag 2 . 5in 6 . 0ga 2 . 5re 0 . 05ru 0 . 05______________________________________ ______________________________________constituents weightof alloys % properties of alloy______________________________________pd 59 . 9 0 . 1 % offset yield strength - 94 , 400 psiau 27 . 0 modulus of elasticity - 20 , 400 , 000 psiag 3 . 0sn 7 . 0ga 3 . 0re 0 . 05ru 0 . 05______________________________________ ______________________________________constituents weightof alloys % properties of alloy______________________________________pd 57 . 9 0 . 1 % offset yield strength - 94 , 400 psiag 29 . 0 modulus of elasticity - 20 , 400 , 000 psiau 3 . 0sn 7 . 0ga 0 . 5in 2 . 5re 0 . 05ru 0 . 05______________________________________ ______________________________________constituents weightof alloys % properties of alloy______________________________________pd 76 . 8 0 . 1 % offset yield strength - 109 , 000 psiau 2 . 5 modulus of elasticity - 16 , 500 , 000 psiag 2 . 5ga 6 . 0in 6 . 0sn 6 . 0re 0 . 1ru 0 . 1______________________________________ ______________________________________constituents weightof alloys % properties of alloy______________________________________pd 82 . 8 0 . 1 % offset yield strength - 66 , 600 psiau 2 . 5 modulus of elasticity - 25 , 300 , 000 psiag 2 . 5ga 6 . 0in 6 . 0re 0 . 1ru 0 . 1______________________________________