Ti₂Al(C, N) Solid Solution Reinforcing TiAl-Based Composites: Evolution of a Core–Shell Structure, Interfaces, and Mechanical Properties

Abstract

In this work, TiAl(C, N) solid solution with lamellar structure-enhanced TiAl matrix composites was synthesized by vacuum arc melting, using bulk g-CN, Ti, and Al powders as raw materials. The phases, microstructures, interfaces, and mechanical properties were investigated. MAX phase of TiAl(C, N) solid solution with lamellar structure was formed. During the melting process, first, CN reacted with Ti to form Ti(C, N) by Ti + CN → Ti(C, N). Then TiAl(C, N) was formed by a peritectic reaction of TiAl(l) + Ti(C, N)(s) → TiAl(C, N). CN is the single reactant that provides C and N simultaneously to final product of TiAl(C, N). The interfaces of TiAl//TiAl(C, N) and TiAl(C, N)//Ti(C, N) display perfect orientation relationships with low misfit values. The microhardness, compressive strength, and strain of best-performing TiAl-10 mol % TiAl(C, N) composite were improved by 45%, 55.7%, and 50% compared with the TiAl alloy, respectively. Uniformly distributed TiAl(C, N) and unreacted Ti(C, N) particles contributed to the grain refinement and reinforcement of the TiAl matrix. Laminated tearing, particle pull-out, and the crack-arresting of TiAl(C, N) are crucial for the improvement in compressive strength and plasticity of the composites.

Investigation on the In Situ Ti2AlC/TiAl Composite with a Homogenous Architecture by Adding Graphene Nanosheets

“…Figure 7b shows that the Vickers hardness of the asprepared composite basically remains between 400~500 HV under different loads (100 gf, 200 gf and 500 gf). Figure 7c shows the comparison diagram of the compression properties between the Ti2AlC/TiAl composite in our work and other TiAl matrix composites [24,27,30,[39][40][41][42]. It can be seen that the mechanical properties of the Ti2AlC/TiAl composite using graphene nanosheets as the carbon source is better than those with graphite as the carbon source.…”

The Effect of Stearic Acid on Microstructure and Properties of (Ti2AlC + Al2O3)p/TiAl Composites

“…Through relevant research reports (TiAl alloys and single-phase reinforced TiAl matrix composites), as shown in Figure 13a, it was found that although the compressive strength of Ti 2 AlC/TiAl composites [38][39][40][41][42] (except for 0.5 wt.% Ti 2 AlC/Ti48Al2Nb [23] and 5 wt.% Ti 2 AlC/TiAl (Nb-C) [20] in Figure 13a) was higher than that of this work, their fracture strains were all less than 0.2, indicating no significant improvement in toughness. Compared to Ti 2 AlC/TiAl composites, the compressive strength and fracture strain of Al 2 O 3 /TiAl composites [30] are almost smaller.…”

“…(a) Comparison of compressive strength and fracture strain of different TiAl matrix composites. (b) Compressive stress-strain relationship of different TiAl matrix composites[20,23,30,[37][38][39][40][41][42][43].…”

Microstructure and Properties of TiAl Composite Coatings Prepared by Laser Cladding under Multi-Phase β0/CoAl2Ti Phase Strengthening

“…In recent decades, several preparation methods were revealed to improve the properties of the TiAl alloy, such as vacuum melting [12], powder metallurgy [13], spark plasma sintering [14], hot isostatic pressing [15], and laser cladding. In recent years, laser cladding experienced rapid development as a surface treatment method with the advantages of its low cost, high efficiency, fast cooling speed, and low dilution rate.…”