Microstructural modification of aluminum-silicon alloy powders during dynamic consolidation
We describe the preliminary results of a study of the dynamic consolidation of a rapidly solidified aluminum-6% silicon alloy powder. The microstructure of this alloy, consisting of a dispersion of silicon precipitates at the boundaries of essentially pure aluminum grains, provides an excellent grid against which to observe the changes induced by shock compaction. Examination of recovered specimens, shocked with either explosives or high velocity projectiles, shows that at low stress, high density is achieved without substantial interparticle bonding, and the microstructure is essentially that of the starting powder. For stresses between 1.7 and 2.6 GPa we observe increasing compact integrity, and the appearance of regions of altered microstrucure at the interfaces between powder particles. Above 4.0 GPa, such modified material is a distinctive feature of the microstructure, and compacts are well bonded. Increasing the stress serves not so much to increase the density as to increase the amount of energy deposited in the specimen. Bonding is the result of the local deposition of energy at particle interfaces during the passage of the shock. This energy may be calculated from the measured Hugoniot (shock compression) curve of the powder. It is suggested that through proper choice of stress level, structurally sound compacts can be formed with limited modification of the powder microstructure. 7 figures.
- Research Organization:
- Lawrence Livermore National Lab., CA (USA)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 6580367
- Report Number(s):
- UCRL-88400; CONF-821223-1; ON: DE83003884
- Resource Relation:
- Conference: 3. conference on rapid solidification processing: principles and technologies, Gaithersburg, MD, USA, 6 Dec 1982
- Country of Publication:
- United States
- Language:
- English
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