Self-propagating high-temperature synthesis of (Al–2%Mn)–10%TiC and (Al–5%Cu–2%Mn)–10%TiC nanostructured composite alloys when doped with manganese powder

Abstract

The paper studies the effect of doping with manganese powder on the production of (Al–2%Mn)–10%TiC and (Al–5%Cu– 2%Mn)–10%TiC nanostructured composite alloys by self-propagating high-temperature synthesis (SHS) of TiC titanium carbide nanoparticles from Ti + C charge in the melt of matrix alloys. First, manganese metal powder was added to the matrix bases of Al and Al–5%Cu composite alloys in the amount of 2 wt%. This improved aluminum base tensile strength from 81 MPa (for the original A7 grade aluminum) to 136 MPa and aluminum-copper base tensile strength to 169 MPa. It was found that when aluminum was doped with manganese only, the SHS reaction proceeded weakly and not completely, and the carbide phase size in the resulting alloy (Al–2%Mn)–10%TiC varied from nanoscale to several micrometers. When 10% Na2TiF6halide salt was added to the SHS charge, the SHS process intensified, but the resulting alloy contained a considerable amount of pores, inclusions of unreacted charge and large agglomerates of TiC ceramic nanosized particles. Similar results were obtained in cases of using Ti + C and Ti + C + 10%Na2TiF6SHS charges, but with joint doping of matrix aluminum with copper and manganese, providing more uniform distribution of the TiC nanodispersed phase. The best results were obtained by reducing the Na2TiF6salt additive to 5 % of the SHS charge mass, which facilitated smoother and complete synthesis of predominantly TiC nanosized particles and the formation of a non-porous uniform microstructure of (Al–5%Cu–2%Mn)–10%TiC composite alloy with an ultimate tensile strength of 213 MPa and 6,6 % elongation.