Ultrafine-grained metastable Ti15Mo alloy prepared by the powder metallurgy technique of spark plasma sintering

Abstract

Titanium alloys are extensively used due to their unique mechanical properties such as high strength, low density and excellent corrosion resistance. Two phase alpha + beta Ti alloys are commonly used in aircraft industry and biomedicine.

Nowadays, Ti-6Al-4V is used for orthopaedic implants. However, vanadium is considered as a toxic element.

Therefore, biocompatible metastable beta-Ti alloys are perspective to replace it. Powder metallurgy is an alternative way for producing titanium alloys.

It has got many advantages such as cost reduction thanks to near-net-shape processing or possibility of composition control. In this work, Ti-15Mo alloy was prepared by cryogenic milling and spark plasma sintering.

Cryogenic milling inserted severe plastic deformation into the material which resulted in ultra-fine grained structure. Spark plasma sintering was performed at temperatures 750°C - 850°C for time periods of 1-3 min.

Achieved material was studied by scanning electron microscopy, x-ray diffraction and via microhardness measurement. The fully dense material was produced and with ultra fine grained microstructure was preserved after sintering at lower temperatures.

Sub-micrometer equiaxed alpha phase precipitates embedded in fine grained beta matrix formed during cooling after the sintering process.