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

53 3

The alloys microstructure was investigated using the method of scanning electron microscopy (SEM) by the ZEISS EVO 40XVP microscope. The composition and elemental distributions of alloys were analysed using energy dispersive X-ray spectrometry (EDS).

Table 1. Chemical composition and size of alloys starting powders.

Chemical composition, % (wt)

Particle size, µm

No

Material

Ме

С total

С free

O

S

1. Titanium carbide 79.8 19.5 0.27 0.31 <0.003

1-2 1-2 1-2 1-2 1-2

2. 3. 4. 5. 6.

Tungsten carbide 93.6 5.95

0.1

0.2

<0.003

Niobium carbide

91.2

8.7

0.15 0.03 <0.003

Nickel

99.8 0.03 99.8 0.05 99.8 0.03

<0.003 <0.003

Chromium Nano Nickel

0.07

4. Results and discussions In all investigated alloys, regardless of the chemical composition and size of the starting nickel powders, specific for titanium carbide-based alloys carbide grains core/rim structure has been found, but their sizes and shapes being different (Fig. 1). The alloy 3 of 24% (wt.) binder is of the finest structure with a large number of homogeneous carbide grains. The alloys 2 and 4 with fine and nano nickel differ, the alloy with nano nickel containing much more fine carbide grains, both homogeneous and those with the core/rim structure, the shape of their cores being usually polygonal.

Fig. 1. SEM images of TiC-5NbC-5WC with 10% (a) (alloy1), 18% (b) (alloy 2), 24% (c) nano Ni-Cr binder (alloy 3) and with 18% (d) fine Ni Cr binder (alloy 4).

Despite some differences, the main microstructure elements of all alloys are the core, rim and binder of black, grey and light colour, respectively. Besides fine homogeneous grey carbide grains were found. In Figures 2-5 the