PSI - Issue 36

Ihor Koval et al. / Procedia Structural Integrity 36 (2022) 51–58 Ihor Koval et al. / Structural Integrity Procedia 00 (2021) 000 – 000

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(Table 2). The line distribution of elements (Fig. 2a) testifies the presence of a core/rim microstructure of carbide grains.

Fig. 3. SEM image alloy 2 (a) with spectrum points, line distribution, EDS result in binder (b).

Table 3. Chemical composition of structure elements in alloy 2.

Core

Rim

Binder

Homogeneous carbide grain

Element

wt%

at%

wt%

at%

wt% 8.75

at%

wt%

at%

C

19.14 49.29 17.47 49.21

31.49

16.24 61.28

46.35 43.84

Ti Cr Ni

76.81 49.60 62.77 44.34 22.60 20.39

0.33 0.35 1.03 2.33

0.20 0.19 0.34 0.39

1.30 3.00 5.73 9.73

0.84 1.73 2.09 1.79

11.06

9.19

2.58 9.24 4.01 6.64

1.70 5.39 1.48 1.24

49.36 36.35

Nb

2.77 5.47

1.29 1.29

W

The binder is a homogeneous solid solution of titanium, chromium, tungsten, niobium in nickel. A significant number of binder lakes is observed in the microstructure, which results in the increase of grain contacts and carbide frame formation. Homogeneous carbide grains are of small sizes 0.4- 0.9 μm and are submicron grains. During sintering, metals of carbides and metals of binder form homogeneous solid solution on titanium base with a significant amount of nickel. The chemical composition of the structural components of alloy 2 with 18% (wt.) NiCr binder, containing 13.5% (wt.) of nano nickel, differs significantly in comparison with others. The core of the carbide grain has the smallest amount of diffuse chromium, nickel and tungsten, while the binder has the largest amount of carbide metals – titanium, niobium and tungsten. With this ratio of binder and carbide, there is a maximum alloying of the binder, which agrees well with the data on mechanical properties, received by Kramar et al. (2018). In the microstructure of alloys 1 and 2, a rim is clearly observed, while in an alloy containing 24% (wt.) of the binder it is, in fact, absent, which testifies a significant effect of 18% (wt.) nano nickel on accel erating of the alloy’s components reverse diffusion process.