Effect of Ni and Cu Intermediate Layers on the Sinterability of a Ti-35Si-10Mg (% at.) Mixture Synthesized by Mechanical Alloying

摘要

A Ti-35Si-10Mg (at.%) mixture was synthesized by mechanical alloying from Ti, Mg, and Si elemental powders. After milling the surface of the particles was chemically modified by the deposition of Ni and Cu thin layers by d.c. magnetron sputtering. Coated and uncoated particles were subsequently consolidated by two different routes: (i) cold isostatic pressing followed by pressureless sintering at T = 1300 °C in vacuum and (ii) cold isostatic pressing followed by hot isostatic pressing at T = 900 °C with an applied pressure of 1500 MPa. The results showed that all samples were formed by a final Ti₃Si₅ + Mg₂Si microstructure. Cu and Ni existed as single phases after hot isostatic pressing. Ni and Cu coatings acted as auxiliary sintering elements during compaction of the mechanically alloyed Ti-35Si-10Mg powders, giving rise to better final compacts. The higher values of hardness and Young.s modulus were obtained for the HIP'ed coated samples, as result of their better densification.