Additive manufacturing (AM) of metallic materials is experiencing a research and commercialization craze in almost all industrial sectors. However, to date, AM has been limited to a small numbers of alloys. With respect to aluminum, two alloys received some attention: Al-12Si and Al-10Si-1Mg. In both cases, fully dense components have been achieved using a continuous-wave selective laser melting system. In this article, a new approach of selective laser melting using a pulsed-laser source as opposed to a continuous-wave laser is proposed. Pulse selective laser melting (P-SLM) would allow for greater control over the heat input and thus further optimization possibilities of the microstructure. P-SLM was demonstrated using the Al-12Si system. Si refinement below 200 nm was achieved throughout the component. Density up to 95% and high hardness of above 135 HV were obtained. The solidification mechanism is also explained.
Purpose -The purpose of this paper is to outline the feasibility of using the electrospark welding (ESW) process to free-form metallic components with nanostructured or amorphous microstructures. Design/methodology/approach -ESW was used to deposit amorphous and nanostructure coatings for high-wear resistance applications. The ESW process was also used to freeform three-dimensional objects via multiple deposition passes. The near-net shape capability is interesting as it significantly reduces the post-processing operations. Findings -This paper demonstrates that it is possible and economically feasible to produce components possessing metastable structures, i.e. nano or amorphous, using the ESW process. Practical implications -The ESW process possesses the ability to manufacture advanced materials and can pattern surfaces to provide appropriate functionality with respect to the service environment. Originality/value -This paper represents a summary of the capabilities of ESW to fabricate advanced materials and is based on the achievements of our laboratory. In particular, results on ESW of amorphous materials and the ability to produce coatings with second phase particles refined to this extent have not been achieved using other manufacturing methods.
The objective of this work was to investigate the effects of hot and cold swaging on the density and mechanical properties of a commercial Al-Zn-Mg-Cu powder metallurgy alloy known as Alumix 431D. To do so, as sintered samples of the PM alloy were swaged under a variety of conditions and characterised. For comparison purposes, equivalent characterisation tests were completed on the chemically similar wrought alloy 7075-T6. Cold swaging was moderately successful provided the as sintered billets were annealed or solutionised before densification.Here, modest improvements in density and tensile properties were noted. Hot swaging proved to be a more effective approach. Optimal properties were achieved when samples were preheated to 470¡10uC. When processed in this manner, a density of 99?6% of theoretical was realised while the tensile and fatigue properties exceeded those of the wrought 7075-T6 alloy tested for comparison purposes.
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