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Powder Metallurgy Consolidation of Manganese-copper Damping Alloys.
Proc 5th Int'l Powder Met Conf Chicago Illinois, 1976 Jun; :1-25
The Bureau of Mines extended its research on development of cast mn- cu damping alloys to p/m consolidation of binary alloys having enhanced damping capacity. Powder techniques also offer potential savings in material and labor. Blends of minus 100-mesh elemental powders were sintered after compacting cold in directional and isostatic presses at pressures up to 50 tsi. Data were obtained for green strengths and densities, and for sintered and densities, and tensile properties as a function of composition, compaction, and sintering temperature and time for alloys containing 55 to 75 wt-pct mn. With 1 pct binder, typical green density of the blends ranged between 76 and 80 pct of theoretical when pressing at 30 or 48 tsi. Green strength increased with compacting pressure and copper content; typical values for the 65 mn-35 cu alloy were between 800 and 1,200 psi. As-sintered tensile strengths ranged to a maximum of 60,000 psi, along with approximately 5 pct elongation, for a 60 mn- 40 cu alloy hydrogen-sintered at 925 deg c for 6 hr. Sintered densities of the alloys ranged between 90 and 96 pct of theoretical. Sintering was successful when holding for only 1 hr at maximum temperatures of 900 deg to 1,025 deg c, dependent on composition; densities and strengths were somewhat lower than for longer sintering times. Characteristic of p/m alloys, the strength and ductility were considerably lower than for equivalent cast alloys. Specific damping capacity was measured for as-sintered, solution- treated, and aged alloys. When aged to the damping condition, alloys containing 6
Proc. 5th Int'l. Powder Met. Conf., Chicago, Illinois, June 27-July 3, 1976, PP. 1-25