Additive manufacturing of metals

Powder metallurgy (PM) of titanium is a potentially cost-effective alternative to conventional wrought titanium. This article examines both traditional and emerging technologies, including the prod...

https://www.tandfonline.com/doi/pdf/10.1080/09506608.2017.1366003

Powder metallurgy of titanium – past, present, and future

In this study, a new processing technique, friction stir processing (FSP) was attempted to incorporate nano-sized Al 2 O 3 into 6082 aluminum alloy to form particulate composite surface layer. Samples were subjected to various numbers of FSP passes from one to four, with and without Al 2 O 3 powder. Microstructural observations were carried out by employing optical and scanning electron microscopy (SEM) of the cross sections both parallel and perpendicular to the tool traverse direction. Mechanical properties include microhardness and wear resistance, were evaluated in detail. The results show that the increasing in number of FSP passes causes a more uniform in distribution of nano-sized alumina particles. The microhardness of the surface improves by three times as compared to that of the as-received Al alloy. A significant improvement in wear resistance in the nano-composite surfaced Al is observed as compared to the as-received Al.

Microstructures and mechanical properties of Al/Al2O3 surface nano-composite layer produced by friction stir processing

Spherical titanium alloy powder is an important raw material for near-net-shape fabrication via a powder metallurgy (PM) manufacturing route, as well as feedstock for powder injection molding, and additive manufacturing (AM). Nevertheless, the cost of Ti powder including spherical Ti alloy has been a major hurdle that prevented PM Ti from being adopted for a wide range of applications. Especially with the increasing importance of powder-bed based AM technologies, the demand for spherical Ti powder has brought renewed attention on properties and cost, as well as on powder-producing processes. The performance of Ti components manufactured from powder has a strong dependence on the quality of powder, and it is therefore crucial to understand the properties and production methods of powder. This article aims to provide a cursory review of the basic techniques of commercial and emerging methods for making spherical Ti powder. The advantages as well as limitations of different methods are discussed.

https://link.springer.com/content/pdf/10.1007/s11837-017-2513-5.pdf

Review of the Methods for Production of Spherical Ti and Ti Alloy Powder

A comparative study of Ti-6Al-4V powders for additive manufacturing by gas atomization, plasma rotating electrode process and plasma atomization

A new atomization process, plasma atomization (P.A.), has been developed to produce fine, spherical powders. Unlike conventional high-pressure atomizers, PA utilizes multiple nontransferred direct-current arc plasmas to accelerate the atomization gas. In the P.A. process, metal wires are fed into the apex of the multiple plasmas, where they melt and are atomized in a single step. This process offers the unique ability to produce spherical powders of reactive metals with a typical average particle size of 40 μm.

Plasma atomization: A new process for the production of fine, spherical powders

The vacuum-plasma-spraying technique presented in this article is suited to produce aluminum-matrix composites with a low coefficient of thermal expansion reinforced with fine ceramic particles, resulting in a uniform particle dispersion and bulk porosity of less than 1.5% in the as-sprayed condition. Plastic deformation of the plates followed by annealing resulted in significant increases in ultimate tensile strength, hardness, and elongation.

The thermal plasma near-net-shape spray forming of al composites

Effect of Y2O3 Content on Sintering of Aluminum Nitride

A new atomization technology was developed for the production of spherical powders and spray-formed shapes. The high enthalpy and high kinetic energy of multiple plasma jets were used to melt, superheat and atomize the raw materials. The plasma atomization process was tested for the production of Ti, Ni, Cu, Cu-Ni, and Al powders. Following optimization of the reactor and nozzle geometries, powders with an average particle size between 50 &#181;m and 150 &#181;m were produced. The powder recovery rate was over 95&#37;, while the particle sphericity was excellent and contained no satellites. In some experiment, TiCI4 was introduced into the exit nozzle and mixed with the Ar plasma forming gas. The highly reactive plasma jets were used to melt and atomize an aluminum wire, and the resulting spray was deposited onto a fixed substrate. The consolidated product was a composite of AI-TiAI3 containing 10 &#37; Ti. The deposit showed excellent mechanical properties.

M. Entezarian

Papers

Plasma atomization: A new process for the production of fine, spherical powders

The thermal plasma near-net-shape spray forming of al composites

Effect of Y2O3 Content on Sintering of Aluminum Nitride

Plasma atomization