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Liquidus in the pseudo-ternary system AlF3–KF–KCl was investigated by thermal analysis. The aim of the study is to modify and improve the Nocolok flux used in aluminum brazing. The mentioned ternary system is divided into three sub-systems: K3Cl3–K3F3–K3AlF6, K3Cl3–K3AlF6–KAlF4 and K3Cl3–KAlF4–AlF3. Ternary eutectics were observed in each sub-system: E1 located at 2.5 mol% AlF3, 44.7 mol% K3F3 and 52.8 mol% K3Cl3 at 584 °C; E2 at 61.7 mol% AlF3, 26.5 mol% K3F3 and 11.8 mol% K3Cl3 at 534 °C; E3 at 63.7 mol% AlF3, 20.7 mol% K3F3 and 15.6 mol% K3Cl3 at 541 °C. A mixture with the composition of point E2 seems to be a good substrate for aluminum brazing flux since this lowered the melting temperature of the Nocolok flux from 558 to 534 °C.

The systems RbF–GaF3 and CsF–GaF3 were re-investigated by DTA and XRD method. In the system RbF–GaF3, with eutectic E1 at 750°C in the location of 8.5 mol% GaF3 and E2 at 749°C in the location of 43.0 mol% GaF3, three compounds Rb3GaF6, RbGaF4 and RbF·2GaF3 were identified and indexed by XRD. The indexed result of α-Rb3GaF6 could not be successfully obtained, β-Rb3GaF6 is tetragonal, a=6.324±0.004, c=8.860±0.003 A. RbGaF4 is orthorhombic, a=9.821±0.006, b=9.517±0.005, c=8.060±0.006 A; RbF·2GaF3 is also orthorhombic, a=9.459±0.005, b=9.336±0.005, c=7.685±0.005 A. In the system CsF–GaF3, with eutectic E1 at 664°C in the location of 7.5 mol% GaF3 and E2 at 675°C in the position of 44.0 mol% GaF3, two compounds were confirmed. α-Cs3GaF6 is orthorhombic with a=10.62±0.02, b=9.959±0.006 and c=5.607±0.005 A; β-Cs3GaF6 is also orthorhombic, a=10.356±0.003, b=8.280±0.003, c=7.621±0.005 A; γ-Cs3GaF6 is tetragonal, a=6.833±0.003, c=9.869±0.002 A; CsGaF4 is orthorhombic, a=8.571±0.007, b=7.575±0.007 and c=6.981±0.006 A.

Phase relations in the systems KAlF 4 –KBe 2 F 5 and K 3 AlF 6 –KBe 2 F 5 have been investigated by DTA and XRD methods. The KAlF 4 –KBe 2 F 5 is a simple eutectic system with the eutectic point at a composition of 80.0 mol% KBe 2 F 5 at 335°C. For the later system, two incongruent compounds 2K 3 AlF 6 ·KBe 2 F 5 and K 3 AlF 6 ·KBe 2 F 5 melting at 448 and 378°C, respectively were confirmed. They have been XRD indexed as both orthorhombic cells with cell parameters a =10.70±0.01, b =10.36±0.01, c =5.85±0.02 A for the former and a =10.499±0.003, b =9.685±0.005, c =7.554±0.005 A for the later. One eutectic point located at 85.0 mol% KBe 2 F 5 at 336°C was also observed.

Phase relations in the systems KAlF4–Rb3AlF6 and KAlF4–Cs3AlF6 were investigated by DTA and XRD methods for the purpose of finding a low melting, non-corrosive aluminum flux. In each system, congruent compounds Rb3AlF6·2KAlF4 and 2Cs3AlF6·3KAlF4 were observed, respectively. Eutectics located at 46 mol% Rb3AlF6 and 511°C, 25 mol% Rb3AlF6 and 512°C for the former system, and 48 mol% Cs3AlF6 and 550°C, 25 mol% Cs3AlF6 and 480°C in the latter were confirmed. The phase α-2Cs3AlF6·3KAlF4 was XRD indexed as having an orthorhombic cell a=10.401±0.003, b=10.078±0.006, c=8.792±0.006 A.

Phase relations in the system CsAlF 4 –KAlF 4 and Cs 3 AlF 6 –K 3 AlF 6 were investigated by DTA and XRD methods. In the system CsAlF 4 –KAlF 4 , two intermediate compounds 3CsAlF 4 ·KAlF 4 and CsAlF 4 ·KAlF 4 were confirmed. The first one was indexed as orthorhombic with a = 9.079 ± 0.003, b = 7.958 ± 0.002, c = 7.648 ± 0.004 A. The second one α-CsAlF 4 ·KAlF 4 is also orthorhombic, a = 10.982 ± 0.005, b = 10.093 ± 0.006, c = 6.160 ± 0.002 A. Among the two compounds and KAlF 4 , two eutectic temperatures e 1 and e 2 are formed. The first eutectic temperature e 1 is located in 42 mol % KAlF 4 at 525°C, and e 2 in 70 mol % KAlF 4 at 510°C. The system Cs 3 AlF 6 –K 3 AlF 6 is a successive solid solution system with the lowest melting point, the composition of which is 75 mol % Cs 3 AlF 6 at 775°C. In the solid solution, compound 2Cs 3 AlF 4 ·K 3 AlF 6 was formed at 656°C, and was indexed as a cubic cell with a = 8.891 A.

Phase relations of the AlF 3 CsF system have been investigated by the methods of DTA and XRD with quenching technique. Four compounds were identified: Cs 3 AlF 6 , CsAlF 4 , CsF·2AlF 3 and CsF·3AlF 3 . Cs 3 AlF 6 melts congruently at 790°C. The first eutectic, E 1 , between Cs 3 AlF 6 and CsF is located in 10.0 mol% AlF 3 at 654°C. CsF·2AlF 3 and CsF·3AlF 3 melt incongruently at 508° and 653°C, respectively. The second eutectic, E 2 , was observed in 42.0 mol% AlF 3 at 471°C. The compound CsAlF 4 formed in the solid eutectic when cooled below 443°C. CsAlF 4 has α and β forms, transformation of which takes place reversibly at 422°C. All phase structures in the system were confirmed by X-ray powder diffraction analysis.

Phase diagram of the system AlF3-RbF was investigated by the methods of DTA, DSC and XRD with quenching technique. Three compounds were identified: Rb3AlF6; RbAlF4 and RbF·3AlF3. Rb3AlF6 melts congruently at 878°C and α ⇋ β transforms reversibly at 340°C. Eutectic E1 between Rb3AlF6 and RbF is located in 10.0 mol% AlF3 at 729°C. RbF·3AlF3 melts incongruently at 745°C, reacting with Rb3AlF6, second eutectic E2 was observed in 48.4 mol% AlF3 at 486°C. The third compound RbAlF4 was formed in the solid eutectic when it cooled below 473°C. A very small thermal effect corresponding to α ⇋ β transformation at 335°C was observed on the DTA curve of this compound. All phase structures in the system were confirmed by X-ray powder diffraction analysis.

The thermal properties of Sn–Pb eutectic alloy doped with Ga, Te or Cu in different particle sizes have been investigated by DTA and XRD methods. It has been shown that SnO was formed on the surface of the eutectic particles doped by Ga at about 475°C. In other cases, SnO 2 was also observed. In larger particles, the oxidation occurred in multiple stages, while simple step occurred only on the smaller sized particles.