MICROSTRUCTURAL FEATURES AND MECHANICAL  AND TRIBOLOGICAL PROPERTIES OF Fe–Cu–Ni–Sn COMPOSITES  PRECIPITATION-HARDENED WITH CrB ADDITION

V.A. Mechnik 1*,
 
N.A. Bondarenko 1,
 
V.М. Kolodnitskyi 1,
 
V.І. Zakiev 2,
 
І.М. Zakiev 2,
 
Е.S. Gevorkyan 3,
 
N.О. Kuzin 4
 

1 V. Bakul Institute for Superhard Materials of the National Academy of Sciences of Ukraine, Kyiv, Ukraine
2 National Aviation University, 1, Liubomyra Huzara ave., Kiev, 03058, Ukraine
3 UKRAINIAN STATE UNIVERSITY OF RAILWAY TRANSPORT, Feuerbach Square 7, Kharkiv, 61001, Ukraine
4 Lviv branch of the Dnipro National University of Railway Transport named after Academician V. Lazaryan, st. Ivanna Blazhkevich, 12a, Lviv, 79052, Ukraine
vlad.me4nik@ukr.net

Powder Metallurgy - Kiev: Frantsevich Institute for Problems of Materials Science NASU, 2021, #03/04
http://www.materials.kiev.ua/article/3216

Abstract

The structural features, hardness, elastic modulus, and wear resistance of the Fe–Cu–Ni–Sn composite materials with different CrB2 contents, produced by cold pressing and subsequent sintering with hot additional pressing, were studied by X-ray diffraction, scanning electron microscopy, microindentation, and tribological testing. The micromechanical and tribological tests were performed on composite samples 10 mm in diameter and 5 mm thick in dry friction conditions. The test results showed that the mechanical and tribological properties of the composites depended on the CrB2 content. The microhardness and elastic modulus varied from 1.2 to 9.2 GPa and from 110 to 245 GPa, respectively, along the samples depending on their composition, resulting from the uneven distribution of the a-Fe, Cu, Cu9NiSn3, NiSn3, and CrB2 phases. The addition of 2 wt.%  CrB2 to the 51Fe–32Cu–9Ni–8Sn composite increased its hardness from 1.2–2.8 GPa to 2.0–4.5 GPa and the elastic modulus from 110–190 GPa to 130–200 GPa and decreased the wear rate from 22.93 × 10–3 to  10.19 × 10–3 mm3 × N1 × m1. The mechanism of increasing the wear resistance of the composite sample containing 2 wt.% CrB2 in comparison with the starting composite was associated with the refinement of iron and copper grains from 5–40 mm to 2–10 mm and the presence of discrete areas of greater hardness and higher elastic modulus. A further increase in the CrB2 content from 2 to 8 wt.% in the composite was accompanied by a simultaneous increase in hardness from 2.0–4.5 GPa to 4.8–9.2 GPa, elastic modulus from 130–200 GPa to 150–245 GPa, and wear rate from 10.19 × 10–3 to 16.68 × 10–3 N–1 × m–1. The higher wear rate of these composites was due to excessive brittleness caused by excessive CrB2 content.


COMPOSITE, CONCENTRATION, DISPERSIVITY, ELASTIC MODULI, FRICTION COEFFICIENT, HARDNESS, STRUCTURE, WEAR RESISTANCE