Nanchang Hangkong University

About: Nanchang Hangkong University is a education organization based out in Nanchang, China. It is known for research contribution in the topics: Microstructure & Alloy. The organization has 7004 authors who have published 5270 publications receiving 62162 citations. The organization is also known as: Nanchang Aviation University.

Effect of solution temperature on the microstructure and mechanical properties of Hastelloy X superalloy fabricated by laser directed energy deposition

Abstract: In this study, the effect of solution temperature on the microstructure and mechanical properties of Hastelloy X fabricated by laser directed energy deposition (LDED) was investigated. As a result, the microstructure of as-deposited (AD) sample was mainly coarse columnar grains directionally growing along the deposition direction. Due to the segregation of Mo and Cr, a lot of Laves phase precipitates in the inter-dendritic. With the increase of solution temperature, the volume fraction of Laves phase gradually decreases. When the solution temperature increased to 1200 °C, the grains of the LDED Hastelloy X superalloy exhibited fully recrystallization, and then became coarse with the solution temperature of 1225 °C. With the dissolution of the Laves phase, the microhardness of the samples drops from 231 ± 5 HV to 211 ± 5 HV. The room temperature tensile results reveal that the as-deposited sample with irregular and long-striped Laves phase presents the worst tensile strength (652 ± 10 MPa) and elongation (30 ± 2%). After heat treatment, the strength and elongation of the LDED Hastelloy X superalloy gradually increased with increasing the solution temperature. When the solution temperature was 1200 °C, the tensile strength of the sample reached the maximum value of 720 ± 1 MPa. With the increase of solution temperature, the elongation increased and then reached the maximum value of 47 ± 2% with heat-treated at 1225 °C. The tensile fracture of LDED Hastelloy X superalloy with solution treatment presented a ductile fracture pattern.

Fabrication of continuous relief micro-optic elements using real-time maskless lithography technique based on DMD

Abstract: A novel method is proposed to fabricate continuous relief micro-optic elements using real-time maskless lithography technique based on digital mirror device (DMD). To evaluate the method, aspheric and spheric micro-lens array was fabricated by following the proposed principle. Firstly distribution of the required exposure dose of lens array was obtained and sliced into a number of contours of equal proportions. Then the contour planes instead of virtual masks were converted into binary image. On the lithography system, the dose accumulated over multiple exposures and the required exposure dose profiles were reconstructed. Finally in the photoresist layer, virtual profiles of lens array were formed, consistent with the original designed elements. The method is feasible and reliable for the fabrication of arbitrary continuous relief micro-optic elements.