Preparation of High-Temperature Multicomponent Alloys by Mechanochemical Synthesis from Refractory Elements

Resumo

Highly dispersed powders of two-phase multicomponent alloys have been prepared by mechanochemical synthesis from Hf_0.5Nb_0.5Ta_0.5Ti_1.5Zr₁ (composition 1) and HfNbTaTiZrMo (composition 2) refractory-metal mixtures in a Fritsch (P-7) planetary mill under an Ar atmosphere. Two solid solutions, with BCC and HCP lattices, were obtained from the five-component mixture (composition 1). In the case of the six-component mixture (composition 2), both solid solutions had BCC lattices. Using compaction by hot isostatic pressing at a temperature of 1200°C, we obtained dense samples. Mechanical tests in compression showed a combination of high strength and plasticity. For sample 1, we obtained a yield stress σ_y = 1317 MPa, compressive breaking stress σ_b = 1340 MPa, and relative breaking spread of 7%. Even better results were obtained for sample 2: σ_y = 2153 MPa and σ_b = 2165 MPa, with δ = 10%.