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This paper deals with the production of aluminium matrix composites through high-energy milling, hot isostatic pressing and extrusion. Spherical powder of the aluminium alloy AA2017 (grain fraction > 100 μm) was used as matrix material. SiC and Al2O3 powders of submicron and micron grain size (< 2 μm) where chosen as reinforcement particles with contents between 5 and 15 vol.% respectively. The high-energy milling process was realised in a Simoloyer mill (Zoz). The milling time was about 4 hours. Hot isostatic pressing (HIP) was used to convert the compound powder into compact material. The extrusion process realises semi-finished products with different geometrical shapes. The stages of the composite powder formation during high-energy ball milling will be discussed by means of metallographic studies. The SEM and TEM results show the microstructure of the compact composites obtained by HIP and extrusion. This study focuses on the dispersion and embedding of reinforcement particles and matrix/reinforcement interfaces. Typical appearances like ferrous contaminations through abrasion of the steel balls and the formation of the spinel phase MgAl2O4 during the subsequent powder-metallurgical processing will be discussed. The semi-finished product exhibits a good particle dispersion and low microporosity. There are no accumulations of the brittle phases nor any microcracks at the interface between reinforcement particles and matrix. [ABSTRACT FROM AUTHOR]

Like harmony in music; there is a dark inscrutable workmanship that reconciles discordant elements, makes them cling together in one society. The products of the glass maker are often aesthetically pleasing, but it would be unfair to claim that glass is intrinsically more attractive than any other type of material. Rather, by its presence in the family of materials, glass extends the range of useful properties and artistic qualities. As has transpired only recently, glass also extends the range of atomic structures in condensed matter, through its unique lack of order. Indeed, it is this atomic-level attribute, rather than the traditional ones of transparency and brittleness, which is now acknowledged as the defining characteristic of this type of material. Oxide glasses such as the common silicate varieties have been in use for at least 4000 years. Glass beads, dating from about 2500 BC, have been found in Egypt and other parts of the Near East, although exploitation of the plasticity of hot glass is more recent. These oxide materials so dominated the scene that the existence of the glassy state was believed to be intimately connected with the presence of covalent bonds. Glass has long been known to be a supercooled liquid, and covalent bonding was regarded as a prerequisite if crystallization was to be avoided. These attitudes underwent radical revision in the 1960s. With the production of metallic examples, it was suddenly realized that a glass need not be transparent, brittle, or insulating. [ABSTRACT FROM AUTHOR]

Gold is for the mistress – silver for the maid – Copper for the craftsman cunning at his trade. ‘Good!’ said the Baron, sitting in his hall, ‘But Iron – Cold Iron – is master of them all.’ It is no exaggeration to say that of all the materials in common use none have had a greater influence on our technological development than metals. Their unique combination of ductility and high electrical and thermal conductivity, together with their ready alloying, qualifies them to play a role for which there is no stand-in. Although they were not the first substances to be pressed into service, their use does go back at least 8000 years. The order in which the various metallic elements were discovered was inversely related to the ease with which they form compounds with the non-metals, particularly oxygen. Thus, with the possible exception of meteoric iron, the first metals known to man were probably gold, silver and copper, these being the only three common examples that actually occur as the metallic element. Conversely, there are metals which so tenaciously hold on to oxygen that they were not extracted from their ores until quite recently. One can imagine early man being attracted by the glint of gold nuggets, and he must have been intrigued by their ease of deformation compared with the brittleness of flint and other stones. The major use of gold has been in ornamentation. [ABSTRACT FROM AUTHOR]

All that is, at all, Lasts ever, past recall, Earth changes, But thy soul and God stand sure, Time's wheel runs back or stops: Potter and clay endure. Of all the different types of material, ceramics might be the most difficult to define. Many would regard them as falling in a small and rather restricted group, and the only examples that come readily to mind would probably be bathroom fixtures, tiles, and the insulators in spark plugs and on telephone poles. The term ceramic actually covers a large variety of natural and artificial substances that share the desirable qualities of hardness and resistance to heat, electricity and corrosion. Just how large and how important the ceramic domain is can be gauged by some of its members: stone, brick, concrete, sand, diamond, glass, clay and quartz. If there has been a lack of understanding of ceramics, it is excusable because even dictionary definitions tend to be rather narrow. We find them restricted to either pottery or porcelain in most cases, and even the better efforts usually go no farther than ‘products of industries involving the use of clay or other silicates’. The word ceramic actually comes from the Greek word keramos, which means burnt stuff. This is too broad a term to be useful here. The best working definition uses a combination of chemical and physical criteria. [ABSTRACT FROM AUTHOR]

Deep in unfathomable mines Of never failing skill He treasures up his bright designs And works his sovereign will The way in which the world came into being, and the time of this important event, have of course been the subject of frequent speculation down through the ages. The issue reveals an interesting schism between oriental and occidental philosophies. The Hindus, for instance, have long maintained that the Earth has existed for thousands of millions of years. In sharp contrast to this, we have the views of Archbishop Ussher and Dr Lightfoot, who, in the middle of the seventeenth century, made a systematic scrutiny of the Bible. They found that a consistent chronological sequence could be established and were able to announce that creation commenced promptly at 9 am on Sunday, 23 October, in the year 4004 BC. The remarkable fact is that this result continued to be taken seriously until not much more than a hundred years ago. And there are many who still believe it. The various scientific methods that have been brought to bear on the question during the past century have successively increased the estimates of the age of the Earth and its neighbouring planets. One can now state, with reasonable confidence, that the solar system is about 6000 million years old. This makes it between a third and a half the age of the Universe itself. [ABSTRACT FROM AUTHOR]

In the period since the First World War the importance of the cities has been reinforced through a rapid expansion of their tertiary functions combined with retention of an important stake in manufacturing, albeit with much diversification. The accessibility of cities has improved through a rapid growth in road transport offering a far more developed system than the railway network, which has been drastically reduced in consequence. This has meant the avoidance of a ‘dual economy’ type of development in which city growth is associated with increasing urban isolation and diminishing influence or contagion throughout the region. But it has, equally, not induced urban growth evenly throughout Scotland: disorderly urban sprawl would not be possible anyway given the relatively stringent planning controls that have evolved during the period but even in the context of government and local authority control of urban layouts it is evident that the growth areas are restricted, especially in the Outer Regions where the urban network remains poorly developed. Thriving industries require the full range of urban amenities such as may usually be found in the regional centres of Scotland, but spread away from these cities is difficult. For an industry can only flourish in the context of favourable environmental circumstances. The spread of industry to the Outer Regions is socially necessary, in view of the reduction in employment in primary sectors which are no longer so labour intensive, but the recent improvements in terms of power and transport are not balanced by a satisfactory urban pattern. [ABSTRACT FROM AUTHOR]