The effect of Mo addition on the liquid-phase sintering of W heavy alloy
- Korea Advanced Inst. of Science and Technology, Daejon (Korea, Republic of). Dept. of Materials Science and Engineering
- Agency for Defense Development, Daejon (Korea, Republic of). Advanced Technology and Research Center
The morphological and compositional changes of grains have been investigated in the initial stage of liquid-phase sintering of W-Mo-Ni-Fe powder compacts. Both large (5.4-{micro}m) and small (1.3-{micro}m) W powders have been used to vary their time of dissolution in the liquid matrix. When 80W-10Mo-7Ni-03Fe (wt pct) compacts of fine (about 1- to 2-{micro}m) Mo, Ni, and Fe and coarse (5.4-{micro}m) W powders are liquid-phase sintered at 1,500 C, the Mo powder and a fraction of the W powder rapidly dissolve in the Ni-Fe liquid matrix. The W-Mo grains (containing small amounts of Ni and Fe) nucleate in the matrix and grow while the W particles slowly dissolve. In this transient initial stage of the liquid-phase sintering, duplex structures of coarse W-Mo grains and fine W particles are obtained. As the W particles dissolve in the liquid matrix during the sintering, the W content in the precipitated solid phase also increases. The dissolution of the small W particles is assessed to be driven partially by the coherency strain produced by Mo diffusion at the surface. During sintering, the W particles continuously dissolve while the W-Mo grains grow. When the compacts are prepared from a fine (1.3-{micro}m) W powder, the W grains dissolve more rapidly, in about 1 hour, and only W-Mo grains remain. These observations show that the morphological evolution of grains during liquid-phase sintering can be strongly influenced by the chemical equilibrium process.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 417869
- Journal Information:
- Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science, Journal Name: Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science Journal Issue: 10 Vol. 27; ISSN 1073-5623; ISSN MMTAEB
- Country of Publication:
- United States
- Language:
- English
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