2017-Sustainable Industrial Processing Summit
SIPS 2017 Volume 5. Marquis Intl. Symp. / New and Advanced Materials and Technologies
| Editors: | Kongoli F, Marquis F, Chikhradze N |
| Publisher: | Flogen Star OUTREACH |
| Publication Year: | 2017 |
| Pages: | 590 pages |
| ISBN: | 978-1-987820-69-0 |
| ISSN: | 2291-1227 (Metals and Materials Processing in a Clean Environment Series) |
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Shock-Assisted Liquid-Phase Consolidation of SHS-Processed Ta-Al Based Composites.
Akaki Peikrishvili1; Laszlo Keckes2; George Tavadze3; Bagrat Godibadze4;1F. TAVADZE INSTITUTE OF METALLURGY AND MATERIALS SCIENCE, Tbilisi, Georgia; 2US ARMY RESEARCH LABORATORY, Aberdeen, United States; 3FERDINAND TAVADZE INSTITUTE OF METALLURGY AND MATERIALS SCIENCE, Tbilisi, Georgia; 4TSULUKIDZE MINING INSTITUTE, Tbilisi, Georgia;
Type of Paper: Regular
Id Paper: 176
Topic: 43
Abstract:
The main purpose of the work presented herein is to combine hot explosive consolidation technology (HEC) with Self-Propagating High-Temperature Syntheses processes (SHS) to obtain Ta-Al and Nb-Al based cylindrical billets with low porosity and improved physical and mechanical properties.
In the first stage of the investigation, we carried out the explosive consolidation of powders at room temperatures to obtain billets with increasing density without cracks and activated surfaces of consolidated particles. In the second stage of the investigation we repeated the same experiments, however, the consolidation was conducted at hot conditions above and below the SHS reaction temperatures of the composite materials. The loading intensity was under 10GPa. The heating temperature was up to 950oC. The heating time before loading was under 30 minutes.
Our investigation showed that the initiation of SHS process and a complete reaction in the Ta-Al powder composites starts at 940oC. In order to fabricate billets at or near the theoretical density with a near-perfect structure and correct cylindrical geometry, it was necessary to load the billets prior to reaching 940oC. Consolidation of the billets above 940oC led to cracking throughout the entire volume of the HEC billet. The application of B4C additives and the HEC of Ta-Al-B4C composites led to the dissolution of the B4C phase, and the formation of TaB, AlCTa2, and TaAl3 phases behind the shock wave front. A reduction of the HEC temperature in the consolidation of Ta(Nb)-Al precursors at 600oC provided only a partial reaction between the precursors the formation of aluminate phases on the surrounding surfaces of the Ta(Nb) particles; this was observed in the entire volume of the HEC billets. The type of intermetallic compounds was found to depend on the percentage of the various precursor phases in the starting composition.
The aforementioned observations, other features of the structure-property-processing relationships for the consolidated Ta-Al and Nb-Al based composites, depending on the loading conditions used, and the set-up and operation of the HEC device will be presented and discussed.