Annealing effect on the structure characteristics of nano-scale damascene copper lines

High-resolution electron backscatter diffraction (EBSD) technique was applied for systematic and detailed study of grain structure and texture changes in various microstructural regions of nano-scale damascene copper lines after annealing in a wide temperature range of 200-500°C. To ensure reliability of the obtained results, large EBSD maps including several thousand grains were obtained in each case. Above 200°C, the grain structure was established to be surprisingly stable in both the overburden layer as well as within the lines. The grain growth in the lines was supposed to be suppressed by pinning effect of second-phase particles entrapped during electrodeposition process

EBSD characterization of cryogenically rolled type 321 austenitic stainless steel

Electron backscatter diffraction was applied to investigate microstructure evolution during cryogenic rolling of type 321 metastable austenitic stainless steel. As expected, rolling promoted deformation-induced martensitic transformation which developed preferentially in deformation bands. Because a large fraction of the imposed strain was accommodated by deformation banding, grain refinement in the parent austenite phase was minima

Annealing behavior of cryogenically-rolled Cu-30Zn brass

The static-annealing behavior of cryogenically-rolled Cu-30Zn brass over a wide range of temperature (100-900 °C) was established. Between 300 and 400 °C, microstructure and texture evolution were dominated by discontinuous recrystallization. At temperatures of 500 °C and higher, annealing was interpreted in terms of normal grain growth. The recrystallized microstructure developed at 400 °C was ultrafine with a mean grain size of 0.8 μm, fraction of high-angle boundaries of 90 pct., and a weak crystallographic texture

Influence of laser power and powder feed rate on the microstructure evolution of laser metal deposited Ti-5553 on forged substrates

In this work, titanium blocks of Ti-5Al-5Mo-5V-3Cr (Ti-5553) have been Laser Metal Deposited (LMD) on forged substrate of the same alloy under varying laser power and powder feed rates. The microstructure has been characterized using optical microscopy, scanning electron microscopy and Electron backscatter diffraction (EBSD) techniques. Microstructure was predominantly large columnar β-grains aligned with the build direction interspersed with fine equiaxed β-grains. Increase in the powder feed rate was found to reduce the average β-grain size and promoted clusters of fine grains to be retained during the deposition of subsequent layers. Increase in the laser power also reduced the average β grain size and promoted greater nano-scaled α precipitates at the substrate interface and initial deposited layers which significantly increased the microhardness in this area. Dendrites exist due to micro-segregation of solutes during rapid solidification which create preferential regions for α nucleation. A difference in texture was observed between specimens manufactured with varying laser powers: a low laser power produced a cube texture and a higher laser power produced a // BD fibre texture

Characterisations of microstructure and residual stress in a customised cranial implant produced by Additive Manufacturing from commercially pure (CP) titanium

Additive manufacturing (AM) is a promising alternative technique to traditional forging and forming processes. Owing to its versatility in making complex parts, AM is an attractive technique for medical applications and hence of a great interest for both engineers and physicians. This is primarily because a 3D model of a part with required dimensions and geometry can be made considering fine details of a patient’s anatomy and specifics of surgery. Given the level of maturity of the traditional manufacturing processes, there are still areas to be improved to make the manufacturing more efficient and cost effective, for example by using AM instead. Characterisation of the final material is very important to understand the gain. The objective of this work is to obtain detailed knowledge of microstructure, mechanical properties, and residual stress (RS) distribution in custom made craniofacial implant produced by AM (Fig.1). For these analyses, electron backscattered diffraction (EBSD), optical microscopy, XRD, hole-drilling based on electronic speckle pattern interferometry (ESPI), micro-hardness tester as well as GOM ATOS were used

Structure evolution of electrodeposited nano-scale copper wires during annealing in wide temperature range

[Abstract unavailable

Microstructure response of cryogenically-rolled Cu-30Zn brass to electric-current pulsing

The effect of transient electric-current pulses (ECP) on the evolution of microstructure and texture of cryogenically-rolled Cu-30Zn brass was determined. The pulsing was shown to lead to recrystallization followed by grain growth. The mean grain size in the recrystallized material was 0.5 μm, thus indicating that cryogenic rolling coupled with ECP is suitable for the production of an ultrafine-grain microstructure in Cu-30Zn brass. The differences in the recrystallization texture in pulsed versus statically-annealed conditions suggested a distinct recrystallization mechanism during ECP

Effect of strain level on the evolution of microstructure in a recently developed AD730 nickel based superalloy during hot forging

Design and control of microstructure of engineering parts made from nickel based superalloys with superior mechanical properties for high temperature applications, require the parts to be subjected to certain thermo-mechanical processing during forging. This often includes sequential straining and annealing at elevated temperatures followed by subsequent aging heat treatments at lower temperatures. In this study, the effect of strain magnitude on the evolution of microstructure during hot forging of a recently developed AD730 nickel based superalloy has been investigated. Microstructural heterogeneity was observed in a forged material manifested in a form of large non-recrystallized grains within the recrystallized matrix that is observed to be dependent on the level of deformation (i.e. strain magnitude). Analyses of microstructure indicated significant reduction in the fraction of low-angle grain boundaries and sub-structures with an increase in the applied strain, suggesting higher fraction of recrystallization with higher levels of strains. It was concluded that the lower strain levels were insufficient to provide enough driving force for complete recrystallization throughout the entire microstructure of the forged material

The grain size distribution investigation of high purity plating Cu wire in depth direction

[Abstract unavailable

Microstructure and residual stress in Ti-6l-4V parts made by different additive manufacturing techniques

Additive manufacturing (AM) also known as solid free form fabrication or additive fabrication, additive layer manufacturing, direct digital manufacturing and 3D printing, is rapidly growing as an advanced manufacturing technology. At present, two major groups of AM techniques, namely powder bed fusion (PBF) and directed energy deposition (DPD), are available. The AM techniques are classified based on the heat source used for the manufacturing process whether it is provided by laser, or an electron beam. Disregarding the AM manufacturing method, the material’s mechanical properties, residual stress level and surface quality are the major limitations preventing the uptake of the technology to produce components for demanding engineering applications. The objective of this study is to obtain more in-depth knowledge of microstructure and residual stress developments in Ti-6Al-4V cylindrical parts made by different AM techniques, and compare the results with parts made through traditional manufacturing practices (i.e. Ti-6Al-4V_ELI). For this purpose, direct comparisons are made between the microstructure and mechanical properties of the materials made by AM techniques and those made by a forging process route