Al–Co–W fusion diagram in the Co–CoAl–W part

Abstract

The fusion diagram of the Al-CoW system in the Co-CoAl-W part was drawn using optical light, differential thermal, X-ray diffraction and electron microprobe analysis data. The alloys were prepared by arc melting. No ternary intermediate phase was found in this partial system above 900°C. The phase equilibria between CoAl and W were established with the peritectic reaction L+W↔CoAl at 1650ºC. The Co-CoAl-W fusion diagram has two isothermal three-phase fields corresponding to four-phase invariant reactions with participation of liquid: L↔Co+ + + +CoAl+ + + +Co 7 W 6 (1380°C) and L+ + + +W↔Co 7 W 6 + + + +CoAl (1490°C). The solidus and liquidus surface projections and the vertical sections for 75 at.% Co and equiatomic Al and W are presented and compared with the isothermal sections at 1200°C and 900°C reported earlier.

Phase equilibria of the Al Co W system at 600 °C

“…Since the discovery of a ternary γ′-Co3(Al,W) intermetallic compound in the Al-Co-W system [1], Co-based alloy has been widely investigated to develop superior high-temperature materials [2][3][4][5][6][7][8][9]. Though the γ′-Ni3Al with the L12 structure is very stable and this phase exists in a wide composition range in the Ni-Co-Al ternary system, the stability of the γ′-Co3(Al,W) phase in the Al-Co-W ternary system remains contradictory [10][11][12][13][14][15][16][17][18]. The reviewed literature will be provided in the "literature survey" session.…”

The Development and Validation of a New Thermodynamic Database for Ni‐Based Alloys

“…To take into account the influence from chemical-ordering on the mobillities in the β (B2) and γ' (L1 2 ) phases, the phenomenological model suggested by Helander and Ågren [16] is used. According to this model Q B is given by (19) The last term counts the summation of contributions to the activation energy from chemical ordering between different i and j atoms, i.e.…”

“…Figure 5 shows the isothermal section at 1173 K and with 30 at% Ni for the quaternary Al-Co-Ni-W system. Symbols represent experimental data of Dmitrieva [19] in Figure 4, and Shinagawa et al [20] in Figure 5. Solid curves are calculated using the present TCNI6, dashed ones by an earlier description present from TCNI4, and dotted ones by the recent description of Cui et al [21].…”

Role of Diagrams of Phase Equilibria in Fabrication of Eutectic Alloys for Mechanical Engineering

“…Грамотное изменение пределов легирования без нарушения фазовой стабильности сплава требовало определения величины совместной растворимости алюминия и вольфрама в кобальте и её изменения с температурой, т.е. построения диаграммы фазовых равновесий сплавов системы Co-Al-W [36][37][38] (рис. 11).…”