MIGROHARDNESS VARIATIONS IN TUNGSTEN-BASED HEAVY ALLOYS AS A FUNCTION OF COMPOSITION AND PROCESSING VARIABLES

摘要

The mechanical response of multiphase tungsten-based heavy alloys cannot be satisfactorily predicted or controlled without an understanding of the behavior of each component phase. This study has utilized commercial heavy alloys produced by both solid state (over a compositional range of 40-90%W with a 7Ni:3Fe binder) and liquid phase sintering (over a compositional range of 91-97%W with a 7Ni:3Fe binder). Additionally, a 25%W alloy was tested in tension as a simulation of heavy alloy matrix response. It has been found that bulk mechanical response of a given heavy alloy is a synergistic product of the properties of the respective phases that result from variation in composition and processing parameters. Hardness data for a number of alloys of commercial interest have been correlated with metallurgical properties of interest for ordnance applications. Annealing/quenching was found to have negligible effect on alloy hardness. The matrix exhibited the greatest hardening in response to deformation whereas the W phase was most significantly affected by aging. The difference in the extent of work hardening between the two phases decreased as the extent of plastic deformation increased. The aging response for swaged bars of 93W-4.9Ni-2.1Fe exhibited a maximum at 500 C for a one hour heat treatment.