THE STRUCTURE AND PHASE COMPOSITION ACQUIRED BY Fe–Ti–Ni–C ALLOYS IN THERMAL SYNTHESIS

    

I. M. Frantsevich Institute for Problems of Materials Science of the NAS of Ukraine, Omeliana Pritsaka str.,3, Kyiv, 03142, Ukraine
Powder Metallurgy - Kiev: Frantsevich Institute for Problems of Materials Science NASU, 2020, #03/04
http://www.materials.kiev.ua/article/3050

Abstract

The structure and phase composition of Fe–Ti–Ni–C alloys obtained in situ by thermal synthesis at 1200 ºC from mixtures of TiH2, Fe, graphite, and Ni powders were studied. The structure of the synthesized alloy represents a skeleton of titanium carbide grains of different stoichiometry with sizes from 0.5 to 16 μm, surrounded by layers of metal reinforcement. Coarse TiC grains are characteristic of the starting mixtures without nickel or with 5% Ni. When Ni content in the mixture increases to 10–20%, the maximum grain size sharply decreases to 6–7 μm. The microhardness of the synthesized alloys decreases with an increase in the nickel content in the mixture to 15%, but slightly increases at 20% Ti in the mixture. The phase composition of the alloys substantially depends on the composition of the starting mixture and includes titanium carbide, cementite component Fe3C, α-iron solid solution, and intermetallic FeNi3 phases (for iron-containing starting mixtures) and Ni3Ti and Ni4Ti (for mixtures with nickel). When Ni content in the starting mixture increases to 10–20%, the lattice parameter and stoichiometry of TiCx slightly decrease and particle size of the alloy car-bide component noticeably increases. The alloys sintered by thermal synthesis were ground to produce composite reinforced steel powders, which can find extensive application in both depositing wear-resistant coatings and fabricating bulky parts by compaction followed by sintering, hot pressing, or hot forging.


CARBURIZED STEEL, HARDNESS, INTERMETALLIC, METAL-MATRIX COMPOSITE, PHASE COMPOSITION, STOICHIOMETRY, STRUCTURE, THERMAL SYNTHESIS, TITANIUM CARBIDE