Abstract
Toward designing a cost-effective advanced powder metallurgy approach, we present a new insight into the efficient utilization of titanium hydride powder, together with pure Ti powder, to prepare high-strength β-titanium alloys. In the present work, Ti–40 mass% Nb alloy was prepared by mechanical alloying of a mixture of pure Ti, titanium hydride, and Nb elemental powders, followed by a carefully designed two-step spark plasma sintering. The role of relative amounts of titanium hydride and pure Ti powders during mechanical alloying, and their effect on the microstructural and mechanical properties of the Ti–40Nb alloy, have been discussed and elaborated. An increasing amount of titanium hydride results in higher powder yield and smaller resultant powder particle size. Subsequent two-step spark plasma sintering resulted in equiaxed microstructure with primarily β phase, wherein the grain size decreased with increasing amounts of titanium hydride powder. The specimen corresponding to alloys prepared using equal amounts of pure Ti and titanium hydride powders resulted in fine-grained structure, exhibiting the best combination of mechanical properties, that is, a combination of highest hardness, high strength, and high ductility.
Highlights
Titanium and its alloys have been widely accepted for a variety of applications, human body implants and automotive body parts, due to the possibility of achieving a unique combination of outstanding mechanical and chemical properties, together with excellent biocompatibility [1,2]
It is interesting to note that an increment of titanium hydride, from 10 mass % to 20 mass %, resulted in a relatively small amount of increment (~4%) in the yield, whereas an increment of titanium hydride up to 30 mass % resulted in approximately 100% powder yield
The β-Ti–40Nb alloy was successfully prepared by mechanical milling of a mixture of pure Ti, pure Nb, and Ti hydride powders, utilizing titanium hydride powder as a Ti precursor as well as process control agent, followed by a two-step spark plasma sintering method
Summary
Titanium and its alloys have been widely accepted for a variety of applications, human body implants and automotive body parts, due to the possibility of achieving a unique combination of outstanding mechanical and chemical properties, together with excellent biocompatibility [1,2]. An alternative powder metallurgy processing approach, based on mechanical alloying (MA) of elemental powders followed by their rapid sintering, such as spark plasma sintering, has been taken into account for synthesizing a wide variety of alloys with fine-grained microstructure and excellent mechanical properties [12,13,14,15,16]. The present work is focused on the development of a novel PM process to prepare β-phase stabilized titanium alloys by utilization of titanium hydride powder followed by two-step spark plasma sintering. The present work deals with the development of a PMtwo-step process, based the mechanical process,ofto prepareofβ-phase stabilized alloys byplasma using sintering a mixture of titanium and milling a mixture elemental powderstitanium-based followed two-step spark process, to prepare titanium hydride powders as a starting powder. The phase, bulk specimens, prepared by the spark plasma sintering of obtained mechanically alloyed microstructure and mechanical properties of the bulk specimens, prepared by the spark powders, were evaluated andmechanically the results are presented and discussed detail. and the results plasma sintering of obtained alloyed powders, were in evaluated are presented and discussed in detail
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