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COST 507 - Repositório Aberto da Universidade do Porto

COST 507 - Repositório Aberto da Universidade do Porto

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3.System Ti-Sn-Al-N. The investigation of the phase equilibria of the boun<strong>da</strong>ry<br />

system Ti-Al-Sn in terms of an isothermal section at 900°C was extended into the<br />

melting range. The existence of the ternary phase Ti5AlSn2 was also observed in as<br />

cast alloys and isotypic phases were also synthesized for the combinations (Ti.Zr.Hf)-<br />

(Sn,Pb)-Al (Ref. 10). The ternary boun<strong>da</strong>ry system Ti-Sn-N was studied at 900°C<br />

employing XRD, SEM-EDX and LOM. No ternary phase was found. Similarly no<br />

quaternary phase was encountered in the experimental investigations of the Ti-Al-Sn-N<br />

quaternary. The finalresults are presented in two papers, (Ref.l 1) and (Ref. 12).<br />

4.System Ti-Ni-Al-N. Detailed investigations concerned the ternary phase equilibria<br />

Ti-Ni-N at 900°C, as only limited information existed for the join TiN-Ni. No ternary<br />

compound exists, however, a large N-uptake up to 11 at%N has been observed from<br />

quantitative ΕΡΜΑ for Ti 2 NiNi. x (x < 0.5) (Ref. 13). Based on the thermodynamic<br />

calculation of the quaternary system in cooperation with group D4 (TU-Clausthal),<br />

specific regions of interest have been investigated in detail: (a) precise solid solubility<br />

limits of Ni in a 2 Ti 3 Al and γΤίΑΙ and (b) isothermal reactions and solidus/liquidus for<br />

selected ternary alloys employing Smith calorimetry. Phase Equilibria in the Ti-Al-Ni<br />

isothermal section at 900°C and 1000°C have shown several discrepancies to earlier<br />

<strong>da</strong>ta in the literature. A compound Ti 3 NiAl 2 N has been identified and characterized by<br />

XRD (Ref. 14).<br />

5.System Ti-AI-Mn-N. The investigation of the phase equilibria in the Ti-Mn-N<br />

ternary at 900°C revealed the existence of hitherto unknown new compounds in the Ti-<br />

Mn binary. A reinvestigation of the binary system in cooperation with group II<br />

(Genua) has been performed with XPD, LOM, EMPA and DTA. A complete<br />

constitutional diagram χ vs. Τ from 600°C to melting was presented (Ref. 15). Three<br />

incongruently melting compounds exist in the region TL^Mnss to TÍ55M1145, and four<br />

peritectic phases have been identified in the region between TiMn 2 and Mn. The<br />

ternary phase equilibria studies were also extended up to 1 bar of N 2 at 900°C (Ref. 16<br />

and Ref. 17). No ternary compound exists.<br />

Ó.System Ti-Al-B-C. With respect to the inconsistencies in literature <strong>da</strong>ta concerning<br />

the calculation of the quaternary system, the section Ti­Al­B was reinvestigated at<br />

1000°C. Quantitative EMPA proved the coecistence of TiB, TÍ3B4 and TiB2 with a2<br />

Ti3­xAll+x (35.5 at.%Al). Based on this new experimental results a thermodynamic<br />

calculation of the System Ti­Al­B was attempted by our partner group DU (MPI­<br />

Stuttgart). Results are summarized in Ref. 18.<br />

7. Further contributions to <strong>COST</strong> <strong>507</strong>­Π. Within the regularly held meetings among<br />

the partner groups in Cost <strong>507</strong>­11, latest results were reported and ad hoc cooperations<br />

were carried out with Cost <strong>507</strong>­11 partners in further systems of interest.<br />

(Ti,V,Ta)-AI-N with <strong>COST</strong><strong>507</strong>­II partner D4 (TU­CIausthal): Logistical assistence<br />

was given regarding the description of these three ternary systems.<br />

W­B, W-B-C with <strong>COST</strong><strong>507</strong> Partner DU (MPI Stuttgart): As part of the quinary<br />

system the subsystems W­B and W­B­C have been assessed and modelled by<br />

63 ­

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