Peng Yang, Dingyong He, Zengjie Wang, Zhen Tan, Hanguang Fu, Wei Shao and Xingye Guo
In this research, the highly dense bulk Cu-5Sn alloy specimens were fabricated using selective laser melting (SLM). This study aims to establish the relationship between laser…
Abstract
Purpose
In this research, the highly dense bulk Cu-5Sn alloy specimens were fabricated using selective laser melting (SLM). This study aims to establish the relationship between laser power (LP), scanning speed (SS) and hatch space (HS) with surface roughness (Ra) and density. To obtain Cu-5Sn alloy formed parts with high strength and low surface roughness. The microstructure and mechanical properties of SLMed Cu-5Sn were investigated.
Design/methodology/approach
The relative density (RD) was optimized using the response surface method (RSM) and analysis of variance. First, the Ra of SLMed formed specimens was studied to optimize the forming process parameters with a good surface. Then, the dense specimens were studied by ANOVA and the RSM to obtain dense specimens for mechanical property analysis.
Findings
Dense specimens were obtained by RSM and ANOVA. The tensile properties were compared with the casted specimens. The yield and ultimate strengths increased from 71 and 131 MPa for the cast specimens to 334 and 489 MPa for the SLMed specimens, respectively. The ductility increased significantly from 11% to 23%, due to the refined microstructure of the SLMed specimens, as well as the formation of many twin crystals.
Originality/value
The Ra, RD and mechanical properties of SLM specimens Cu-5Sn were systematically studied, and the influencing factors were analyzed together. This study provides a theoretical and practical example to improve the surface quality and RD.
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Muhammad Waqas, Dingyong He, Zhen Tan, Peng Yang, Mu Gao and Xingye Guo
The selective laser melting (SLM) technique, as a typical additive manufacturing process, is widely used for the fabrication of metallic biomedical components. In terms of…
Abstract
Purpose
The selective laser melting (SLM) technique, as a typical additive manufacturing process, is widely used for the fabrication of metallic biomedical components. In terms of biodegradability, zinc and its alloys represent an emerging generation of metallic materials for biomedical implants. The purpose of this paper is to obtain the Zn and Zn10Mg alloys with high mechanical properties using the SLM technology. The relationship between the processing parameters and the porosity of pure Zn and Zn10Mg alloy samples was investigated.
Design/methodology/approach
The samples were fabricated using SLM technology working in an inert gas closed chamber. Preliminary experiments were conducted to analyze the laser power and gas flow on evaporation, single track form and porosity. To evaluate the influence of factors on relative density, the response surface methodology was applied.
Findings
The satisfactory results of the proposed method were achieved, in which the relative density of the components reached up to 99.63%, and compression strength reached 214 ± 13 MPa under optimal processing conditions.
Originality/value
Zinc is categorized by its low melting and boiling point, which leads to the high porosity of the components. It is difficult to prepare the Zn alloy samples with high relative density using SLM technology. This work successfully achieved dense Zn and Zn10Mg samples and investigated their microstructure, mechanical properties and corrosion behavior.
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Shipeng Yan and Fabrizio Ferraro
Socially responsible investing (SRI) funds depart from mainstream finance by incorporating environmental, social, and governance considerations, but their success varies across…
Abstract
Socially responsible investing (SRI) funds depart from mainstream finance by incorporating environmental, social, and governance considerations, but their success varies across regions. By using a historical comparative case design, we identify an empirically puzzling phenomenon in China: despite an initially favorable resource environment and the presence of socially skilled institutional entrepreneurs, SRI wanes over time in Hong Kong but survives in Mainland China where initial resource endowments and actors’ social skills were inferior. By comparing four periods of SRI development, we reveal how state sustainable development policies, a change in the institutional context, led unintentionally to a shared orientation and a public pool of resources, which sustained the SRI niche. Our paper contributes to research on market emergence, institutional change, and cultural entrepreneurship.