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As-cast microstructures and solidification paths of the Nb-Si-Ti ternary alloys in Nb5Si3-Ti5Si3 region
Abstract The as-cast microstructures and solidification paths of the Nb-Si-Ti ternary alloys in the NbsSi3-TisSi3 region were investigated. Since there exist some isomor- phous compounds in the NbsSi3-TisSi3 region, such as aNbsSi3 with B3Cr5 prototype, 13NbsSi3 with Si3W5 pro- totype, 7NbsSi3 with...
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Published in: | Rare metals 2013-10, Vol.32 (5), p.502-511 |
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Main Authors: | , , , , |
Format: | Article |
Language: | English |
Subjects: | |
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Online Access: | Get full text |
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Summary: | Abstract The as-cast microstructures and solidification paths of the Nb-Si-Ti ternary alloys in the NbsSi3-TisSi3 region were investigated. Since there exist some isomor- phous compounds in the NbsSi3-TisSi3 region, such as aNbsSi3 with B3Cr5 prototype, 13NbsSi3 with Si3W5 pro- totype, 7NbsSi3 with MnsSi3 prototype, and TisSi3 with MnsSi3 prototype, the primary solidification areas of these compounds were not typically indentified in previous experiments. In the present paper, the microstructure observation, the phase identification, and the composition measurement were performed using scanning electron microscopy (SEM), X-ray diffraction (XRD), and electron probe microanalysis (EPMA), respectively. No ternary compound is found. There exist three primary solidification areas, 13Nbs_x(Ti)xSi3, ~Nbs_x(Ti)xSi3, and Tis-x(Nb)xSi3 in the NbsSi3-TisSi3 region. Together with the literaturereported experimental data and optimization results, the liquidus projection of the whole Nb-Si-Ti ternary system is constructed, and totally ten primary solidification areas-- diamond-Si, Nb1-x(Ti)xSi2, Ti1-x(Nb)xSi2, Ti1-x(Nb)xSi, Ti5-x(Nb)xSi4, βNb5-x(Ti)xSi3,αNb5-x(Ti)xSi3, Ti5-x (Nb)xSi3, (Nb,Ti)3Si, and BCC--and nine transitional invariant reactions-L + Nb1-x(Ti)xSi2 → Ti1-x(Nb)x Si2 + Si, L + Nb1-x(Ti)xSi2 → Ti1-x(Nb)xSi2 + Ti5- (Nb)xSi4, L + Ti5-x(Nb)xSi4 → Ti1-x(Nb)xSi2 + Ti1-x (Nb)xSi, L + 13Nb5-x(Ti)5Si3→ Nb1-x(Ti)xSi2 + Ti5-x (Nb)xSi4, L + βNb5-x(Ti)xSi3→b5-x(Ti)xSi3 +Ti5-x (Nb)xSi4, L + αNb5-x(Ti)αSi3 → Ti5-x(Nb)xSi3 + Ti5-x(Nb)x Si4, L + αNb5-x(Ti)xSi3 →βNb5-x(Ti)xSi3 + Ti5-x(Nb)xSi3, L + βNb5-xTb-xSi3 → Ti5-x(Nb)xSi3 + (Nb,Ti)3Si, and L + (Nb,Ti)3Si → Ti5-x(Nb)xSi3 + BCC are confirmed. |
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ISSN: | 1001-0521 1867-7185 |
DOI: | 10.1007/s12598-013-0143-9 |