the archimedean method and an average value was calculated from the results of more than 5 experiments under each condition the theoretical density was calculated from the theoretical density of the composing elements of the heavy alloy in consideration of the composition of the heavy alloy assuming that no pores exist as shown in table 1 test pieces 1 and 2 obtained by the sintering method of the present invention had almost 100 theoretical density although the test pieces had a greater content of manganese than test pieces 4 5 6 obtained by the conventional art process the reason is that the formation of pores due to the manganese not deoxidized during sintering is prevented by separating the manganese which is oxidized to a relatively greater extent than the powders of tungsten nickel and iron a photograph of the microstructure of the test pieces sintered by the above described process shows the formation of few pores in the w ni fe mn heavy alloy more clearly fig6 a shows that the microstructure of test piece 3 fabricated in accordance with the method of the present invention has few pores although it has a high content of mn table 1______________________________________method ntp mn aa md td ntd______________________________________present 1 1 0 17 53 17 53 100invention 2 3 0 17 07 17 07 100 3 5 0 16 62 16 65 99 8conventional 4 0 5 17 00 17 47 98 5art 5 1 0 17 25 17 53 97 4 6 2 5 16 80 17 61 95______________________________________ lt note gt ntp number of test pieces mn aa mn added amount weight md measured density g cm sup 3 td theoretical density g cm sup 3 ntd relative theoretical density next another sintering method will.