A novel type of Co–Ti–Cr-base γ/γ′ superalloys with low mass density

Microstructure and Properties Evolution of Co-Al-W-Ni-Cr Superalloys by Molybdenum and Niobium Substitutions for Tungsten

“…pct W approximately lowers the alloy density by around 0.11 g/cm 3 , slightly less than Nb by about 0.15 g/cm 3 . The density of 1W4Mo and 1W4Nb are close to the recent reported low-density Co-based alloys Co-Al-Mo, Co-Ti-Cr, Co-Ti-V, C-Nb-V, [25][26][27][28][29] etc. and commercial Co-and Ni-based alloys IN718, U720Li, etc.…”

“…The volume fraction in 5W is 48.5 pct, which continuously declines to 32.7 pct in 1W4Mo with increasing Mo content but raises to 74.4 pct in 1W4Nb containing higher content of Nb ( Figure 5). Co-base alloys [24,27] Figure 4 shows the BSE images at grain boundary of alloys with the replacement of W by Mo and Nb after aging heat treatment of 900°C for 24 hours and 750°C for 1000 hours. Limited number of bright contrast blocky precipitates are observed at grain boundary in 5W.…”

“…[5,[14][15][16][17][18][19][20] Neumeier et al [21] and Knop et al [22] reported Co-based superalloys with better high-temperature strength than most of polycrystalline Ni-based superalloys, but the density is as high as 8.8 and 8.52 g/cm 3 . As a result, variant alloy systems with low or zero W content have been investigated, developing alloys based on Co-Al-Mo, [23,24] Co-Ge-W, [25,26] Co-Ti-Cr, [27] Co-Ti-V, [28] Co-Nb-V, [29] and so on. Accordingly, the density has been decreased from 9.5 to 8.5 g/cm 3 , close to those of most commercial Ni-based and Co-based polycrystalline alloys.…”

On the Effect of Nb on the Microstructure and Properties of Next Generation Polycrystalline Powder Metallurgy Ni-Based Superalloys

“…[4][5][6] Despite this, superalloys based purely on the Co-Ti system are unsuitable for service at temperatures over 800°C due to limits in their microstructural stability or their balance of mechanical properties. [7][8][9][10] However, co-additions of Co and Ti to conventional Ni-based superalloys have been found to confer significant strength benefits to the material. [11][12][13][14][15] In one such study, increasing the concentration of Co and Ti in RR1000 resulted in yield and tensile strengths that were~20 pct greater than that of conventional RR1000.…”

Mechanical and Thermal Properties of Low-Density Al20+xCr20-xMo20-yTi20V20+y Alloys

“…Currently, most widely used alloys are nickel-based with working temperatures of 1200 K-1600 K. The performance of traditional nickel-based superalloys is thus limited to high-temperature applications (>1900 K), due to their low melting temperature and high density [1,2]. In past years, several high-temperature nickel-based superalloys such as Inconel 625 [3], SSR 99 [4], and Co-Ti-Cr [5] have been widely investigated. These reports show that while they have excellent mechanical properties, they also have high density.…”