in accordance with this invention , low oxygen electrolytic manganese chip having the normal alpha phase ( allotropic form ) is heated to a temperature of about 1305 ° to about 1990 ° f ., and then rapidly quenched to ambient temperatures , as for example in water , whereby the manganese is converted to the beta phase . preferably , the manganese chip is heated to a temperature of about 1400 ° to about 1600 ° f . and quenched in water . the resulting beta manganese is then crushed to produce a 30 mesh × down powder . advantageously the powder has a relatively uniform or controlled particle size and contains less than about 50 % by weight of - 325 mesh material . by way of contrast when alpha manganese chip is similarly crushed , the resulting powder contains on the order of 75 %- 325 mesh particles . such reduction in the fines content of beta manganese powder produced according to this invention was unexpected since heat treatments do not ordinarily have a significant effect on the particle size of the crushed metal . by reason of its more uniform particle size , beta manganese powder is particularly suitable not only for forming manganese - aluminum compacts according to this invention as more fully described hereinbelow , but also in making welding rods where particle size specifications for manganese powder are quite rigid . the beta manganese after being crushed will generally have a particle size distribution similar to that shown in table i . table i______________________________________ % retained on or betweenmm . ( mesh ) sieves______________________________________0 . 420 ( 40 ) 7 . 80 . 297 ( 50 ) 19 . 40 . 210 ( 70 ) 19 . 80 . 149 ( 100 ) 13 . 80 . 105 ( 140 ) 9 . 40 . 074 ( 200 ) 7 . 50 . 044 ( 325 ) 7 . 8 - 0 . 044 ( 325 ) 14 . 5______________________________________ although it is generally convenient to produce beta manganese by means of the above described heat treatment , the beta structure can also be obtained by controlled cooling of molten manganese . in the alloying additions according to this invention it is generally preferable to have the beta manganese present in the form of the metal per se . however , the beta manganese can also be in the form of an alloy of manganese and aluminum . in this regard , it is known that when manganese is present in such an alloy in an amount of from 75 to about 98 percent , the manganese is in the beta form . a particularly preferred alloy for use in making the compacts comprises about 95 percent manganese and 5 percent aluminum . the aluminum constituent of the compacts should , like the beta manganese constituent , be substantially pure , i . e . comprise at least 95 percent aluminum , and also should be finely divided . aluminum powders where the average particle size is 40 mesh × down are particularly suitable for forming the compacts of this invention . a mixture of the beta manganese and aluminum particles is then prepared and the mixture is compacted to form coherent briquettes or pellets . the pellets or briquettes preferably have sufficient density so that they sink of their own weight in the bath or molten aluminum . there is commercially available a variety of pelletizing and briquetting equipment which may be used to form the compacts of this invention . ordinarily the compacts will contain from about 50 to about 90 percent beta manganese and from about 10 to about 50 percent aluminum , said percentages being by weight based on the total composition of the compact . preferably the compacts contain from about 70 to about 80 percent beta manganese and from about 20 to about 30 percent aluminum . when the beta manganese is present in the form of an alloy of aluminum and manganese , at least 10 percent of the compact should comprise powdered aluminum . in use , the compacts are added to the molten aluminum which generally is at a temperature in the range of about 1280 ° to about 1500 ° f . after addition of the compacts the bath should be stirred , at least periodically . generally compacts in an amount of from about 15 to about 35 pounds per ton of aluminum may be used to obtain desirable aluminum alloys of improved strength . the compacts may be of any shape , but should not be so large in dimensions as to interfere with rapid dissolution of the manganese . thus , suitable compacts are pillow - shaped briquettes having a thickness not exceeding about 1 / 2 inch and a length and width on the order of from about 1 / 2 to about 21 / 2 inches . to more particularly illustrate the present invention various tests were performed and the data obtained are shown in the following examples . separate batches of low oxygen electrolytic manganese chip having the normal alpha phase , one bath having a sulfur content of 0 . 03 percent and the other of 0 . 07 percent , were heated to 1000 ° f . to effect hydrogen removal , air cooled to ambient temperatures , and ground into a powder having a particle size of 30 mesh × down . x - ray diffraction patterns of the powder from each batch thus prepared showed the manganese to have the alpha structure . 77 parts by weight of the manganese powder from each batch were mixed with 23 parts of an aluminum powder of high purity having a particle size of 40 mesh × down , and the mixtures were compacted into coherent briquettes 1 inch in length by 5 / 8 inch in width and 3 / 8 inch in thickness . each briquette weighed approximately 17 grams . the procedure of example 1 was repeated with the exception that prior to air cooling , the manganese chip in each batch was heated to 1500 ° f . x - ray diffraction patterns of the powder from each batch showed the manganese to be alpha manganese . briquettes similar to those of example 1 , each containing 77 parts manganese from one or the other of the two batches and 23 parts aluminum , were prepared . the procedure of example 1 was repeated with the exception that the manganese chip in each batch was heated to 1000 ° f . followed by water quench . x - ray diffraction patterns of the manganese powder after crushing for each batch showed it to have the alpha phase . briquettes similar to those of example 1 , containing 77 parts manganese from one or the other of the two batches and 23 parts aluminum were prepared . the procedure of example 1 was repeated with the exception that the manganese chip in each batch was heated to 1500 ° f . followed by water quench . x - ray diffraction patterns of the manganese powder from each batch showed the manganese to have the beta phase . briquettes similar to those of example 1 , containing 77 parts manganese from one or the other of the two batches and 23 parts aluminum , were prepared . briquettes of examples 1 , 2 , 3 and 4 were added to separate 10 kilogram batches of molten aluminum . the number of the particular briquettes added in each instance was nine . one - half of the baths were at 1300 ° f . while the other half were at 1400 ° f . briquettes similar to those of examples 1 to 4 containing untreated manganese were also introduced to molten aluminum baths as a control . solution rate of the respective briquettes was measured by determining manganese recovery in weight percent 15 minutes subsequent to introduction of the briquettes into the molten aluminum . the results are set forth in table ii , below : table ii______________________________________ mn recovery (%) at 15 minutes 1300 ° f . 1400 ° f . example a * b ** a * b ** ______________________________________1 93 . 4 93 . 0 87 . 6 95 . 42 96 . 7 93 . 4 93 . 8 94 . 03 97 . 2 95 . 4 93 . 9 95 . 84 96 . 9 95 . 8 100 . 5 97 . 3control 86 . 2 90 . 4 78 . 6 83 . 7______________________________________ * manganese containing 0 . 03 % sulfur . ** manganese containing 0 . 07 % sulfur . the results , presented in table ii , for 1300 ° f . and 1400 ° f . melt temperatures , show that increased rate of solution and improved manganese recoveries are obtain with manganese - aluminum briquettes according to this invention containing beta manganese . manganese - aluminum briquettes were prepared according to examples 2 and 4 . in addition , briquettes of the same composition ( 77 % manganese / 23 % aluminum ) in which the manganese had not been subject to any heat treatment were prepared and used as a control . each type of briquette was added alone to 400 pound aluminum melts at 1300 ° f . after addition of the briquettes each melt was stirred continuously for 1 minute from 2 to 3 minutes after addition and again from 7 to 8 and 12 to 13 minutes after addition . three samples of the aluminum were taken from each melt at about 5 , 10 and 15 minutes after addition of the briquettes . solution rate , in terms of manganese recovery , were determined by analysis of the samples taken at 5 , 10 and 15 minutes after briquette addition and the results are given in table iii , below : table iii______________________________________ manganese recovery (%) sample 5 mins . 10 mins . 15 mins . ______________________________________control 73 80 861500 ° f ., air cool ( αmanganese ) 74 97 1001500 ° f ., water quench ( β manganese ) 87 100 100______________________________________ the data in table iii show the improvements in terms of rate of solution of manganese and manganese recovery made possible by the present invention . an alloy of manganese and aluminum comprising 95 percent , by weight manganese was prepared by melting low oxygen manganese and aluminum in a magnesium oxide crucible using a cryolite flux , and cooling the resulting alloy to room temperature . in such an alloy the manganese is in the beta form . the alloy was crushed to 30 mesh × down and 770 grams thereof was mixed with an atomized aluminum powder having a particle size of 40 mesh × down . the mixture was compacted into coherent briquettes 1 inch in length by 5 / 8 inch in width and 3 / 8 inches in thickness . each briquette weighed approximately 17 grams . the procedure of example 7 was repeated with the exception that 811 grams of the manganese - aluminum alloy was combined with 189 g . of the aluminum powder . the procedure of example 7 was repeated with the exception that 770 grams of alpha manganese were used in place of the manganese - aluminum alloy . briquettes of examples 7 , 8 and 9 were added to separate 10 kilogram batches of molten aluminum , one - half of which were at 1300 ° f . while the other half were at 1400 ° f . solution rate of the respective briquettes was measured by determining manganese recovery in weight percent 15 minutes subsequent to introduction of the briquettes into the molten aluminum . the results are given in table iv below : table iv______________________________________ mn recovery 1300 ° f . 1400 ° f . ratioexample mn / al % % ______________________________________7 81 / 19 97 . 8 97 . 68 77 / 23 96 . 5 96 . 49 * 77 / 23 91 . 6 90 . 5______________________________________ * control the results as given in table iv show improved manganese recoveries are obtained using mn - al briquettes containing beta manganese in the form of a mn - al alloy , as compared to similar briquettes in which the manganese is alpha manganese .