There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

Phd by thesis

Additive manufacturing of metallic components – Process, structure and properties

Unlike conventional materials removal methods, additive manufacturing (AM) is based on a novel materials incremental manufacturing philosophy. Additive manufacturing implies layer by layer shaping and consolidation of powder feedstock to arbitrary configurations, normally using a computer controlled laser. The current development focus of AM is to produce complex shaped functional metallic components, including metals, alloys and metal matrix composites (MMCs), to meet demanding requirements from aerospace, defence, automotive and biomedical industries. Laser sintering (LS), laser melting (LM) and laser metal deposition (LMD) are presently regarded as the three most versatile AM processes. Laser based AM processes generally have a complex non-equilibrium physical and chemical metallurgical nature, which is material and process dependent. The influence of material characteristics and processing conditions on metallurgical mechanisms and resultant microstructural and mechanical properties of AM proc...

Laser additive manufacturing of metallic components: materials, processes and mechanisms

A method of treating a titanium aluminide alloy having a single alpha phase field and being capable of producing a massively transformed gamma microstructure by subjecting the alloy to a temperature cycle that produces the massively transformed microstructure having a refined microstructure; the method being characterised in that oxygen securing means are provided within the alloy to prevent diffusion of oxygen to the grain boundary.

An alloy and method of treating titanium aluminide

In a hot isostatic pressure bonding/forming process suitable for an integrally bladed disc assembly 2 in which pre-formed blades 6 are joined to the circumference of a disc 4, a cavity is defined at the joint location, filled with alloy powder and hot isostatic pressure is applied to consolidate the powder into a union piece 10 to form the joint 11 in which the consolidated powder is joined to both the disc 4 and the blade 6. A number of blades 6 may be joined simultaneously at locations spaced apart around the disc circumference.

Method of manufacturing a component using hot isostatic pressure

A method of forming a product from a first component comprising a void region filled with a salt by joining the first component to a second component using pressure and then removing the salt by melting. Figure 1 shows an aerofoil blade 1 with a plurality of passages 3. The passages 3 are filled with a powdered salt 4 and then welded closed. An end of the blade 1 is located in an end of a mould 2 which is filled with a powdered alloy 6. The blade 1 and mould 2 are hot isostatically pressed, thereby sintering the powder 6 and joining it to the blade 1. The welds 5 are then opened and the salt 4 removed. Figure 2 shows powder preform 26 which comprises a cavity 23. A reinforcing box, web, rib or mesh 20 lies within the cavity 23, along with a salt 24. The perform 26 is hipped and then the salt 24 removed through a drain hole 28 drilled into the body. An alloy may be used instead of a salt.

A method of joining two components to form a product

Samples of Ti-15Cr and Ti-15V-3Sn-3Al-3Cr (wt%) containing controlled additions of carbon up to 0.2wt% and different oxygen contents have been quenched and aged at temperatures between 400 and 600°C. Optical, scanning and analytical transmission electron microscopy have been used to characterise the microstructures of the quenched and aged samples. Hardness testing has been used to follow the kinetics and extent of age hardening, which are accelerated in Ccontaining samples. The addition of carbon results in the formation of Ti(CxOy) precipitates which pin grain boundaries in forged samples so that the grain size in the quenched C-containing samples is about a factor of ten less than that in the C-free samples. In the C-free samples coarse grain boundary alpha tends to form, but in the C-containing samples alpha precipitation is more uniform throughout the beta grains. The extent of omega precipitation is very different in the two alloys; the Ti-15Cr alloy forms athermal omega in the as-quenched samples and large omega precipitates are formed on ageing at 400°C. No evidence for omega has been obtained in the Ti-15-3. The hardening responses and microstructural observations are interpreted in terms of the different grain boundary oxygen contents in the C-containing and C-free samples and the different roles of omega and of carbon in the two alloys.

Ageing of C-Containing and C-Free Ti-15Cr and Ti-15-3

This chapter is aimed at providing a brief overview of near net shape forming of aeroengine components. Among many near net shape-forming processes, this chapter will focus on direct laser deposition (DLD) and net shape HIPping (NSHIPping). DLD has applications in the area of building small components or for precision repair, and NSHIPping is mainly used for manufacturing large components, especially from Ti or Ni alloys. The chapter will cover an introduction to these technologies, their pros and cons, the mechanical properties of the components manufactured using these processes, and the issues for their application in the aerospace industry.


Keywords:

manufacture of aeroengine Ni/Ti components;
advanced powder processing;
net shape laser fabrication;
net shape HIPping

Xinhua Wu

Papers

An alloy and method of treating titanium aluminide

Method of manufacturing a component using hot isostatic pressure

A method of joining two components to form a product

Ageing of C-Containing and C-Free Ti-15Cr and Ti-15-3

Near Net Shape Forming of Aeroengine Components