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In the present work, 16% chromium AISI 430 ferritic stainless steel weld produced under different conditions of energy input and metal powder addition using TIG torch melting is investigated for carbide precipitation. A Box Behnken experimental design paradigm is invoked with current, speed and metal powder concentration as the primary variables while type of powder is the categorical variable. The result indicates that for a given concentration of metal powder in the melt pool, the sensitized geometry increases with energy input. Titanium as well as the mixture of aluminum and titanium powders reduces the width of the sensitized zone while aluminum powder increases the width of the zone. Titanium powder prevents the development of completely ditched structure in the high temperature heat affected zone (HTHAZ) whereas aluminum powder accelerates the formation of ditched structure in the HAZ.

Eutectoid steel with full pearlitic microstructure is hard and strong. Near eutectoid steels containing pearlite and proeutectoid ferrite or cementite micro-constituents do not give that unique properties. Isothermal transformation treatments with precise control of cooling temperature produce fully pearlitic microstructure of fine lamellar spacing in near eutectoid steels. The cold drawn wire of this fine pearlite steel is one of the strongest materials used in music wire where the strings are tuned under tension. Carbon–manganese steels containing 0.65–0.84%C and 0.70–1.10%Mn transform to pearlite upon air-cooling, which develops wear resistance and hardness properties suitable for rails application. These properties further increase with finer interlamellar spacing generated by reducing transformation temperature.

Cobalt-based alloys are used as wear resistant, magnetic, and high strength materials. Alloying with nickel, chromium, Ta, W, Nb and Mo develop some extremely important properties such as fatigue and creep strength at high temperatures, and resistance to sulfidation. 20–30% Cr additions provide oxidation and hot corrosion resistance. In cobalt alloys hardening occurs by precipitation of carbide during heat treatment. A new class of ?–?' cobalt-based superalloy has been reported and the optimum composition of the quaternary alloy is Co–10Al–5Mo–2 Nb. It has superior mechanical properties at high temperatures than the existing polycrystalline Co-based and Ni-based superalloys. Most of the commercial cobalt alloys are known with trademarks. The Stellite trademark, which was applied to the first cobalt wear alloys, is still in use. The Unified Numbering System has been used to designate a number of commercial cobalt alloys.

Gold is the most precious metal and widely used for monetary commodity. Pure gold is very soft, malleable, and highly resistant to corrosion. Alloying with silver, copper, nickel, platinum, zinc, and thermal processing make gold stronger. Gold alloying generates several attractive colors for jewelry applications. Purity of gold is designated by karat, and 24 karat (24 K) gold is 1000 fine or pure gold. Gold has other uses in dentistry, semiconductor industries, scientific equipment, and sensing metal ions in environmental and bio applications.

Aluminum is very attractive in many engineering applications for its low density. By alloy addition, cold working and/or heat treatment can develop a high specific strength. Numerous aluminum alloys are available as cast, wrought and/or heat-treated products for various applications. These materials are classified using a standard designation system; the wrought having a 4-digit system, and the castings having a 3-digit and 1-decimal place system. The first digit identifies the alloy group and the second two digits identify composition. Letters added as suffixes to the alloy number indicate various tempers developed by different treatments. One or more digits following the letter indicate subdivisions of the tempers, when they significantly influence the characteristics of the alloy.

Nickel is a versatile element and it alloys with most metals. Nickel alloys have wide variety of applications including low-expansion alloys, electrical resistance alloys, soft magnetic alloys, and shape memory alloys. However, majority of these alloys are employed in places where they are subjected to harsh environments at high temperatures. The nickel–chromium alloys particularly are popular for applications in power plants and turbine engines because of its excellent strength and resistance to corrosion and oxidation at high temperatures. Commercial nickel alloys developed by different producers for specific applications are marketed using individual trademarks with various identification systems. A generic coding number for these alloys have been designated with the Unified Numbering System, although it does not define any requirements for form, condition, or properties.

Silver is the most plentiful of the precious metals. It is a very soft metal and has high resistance to corrosion and oxidation properties. The hardness and strength of this material are enhanced by alloy additions and heat treatments. Silver has wide applications in jewelry, decorative art, coins, and tableware. Because of high electrical conductivity, high temperature mechanical and functional properties, silver alloys have extensive use in electronic industries, brazing, heavy-duty bearings, and electrical contracts. Alloys of silver-metal oxides are mainly used in low voltage electrical switching devices like relays, installation and distribution switches, appliances, industrial controls, motor controls, and protective devices properties. Silver alloys are developed as substitute of high cost gold alloys for dental applications.

The properties of electroplated copper film have been investigated as a function of annealing temperatures together with the diffusion barrier performance. Electroplated copper films on copper and tungsten seed materials were annealed from 300 to 700 °C in N2 atmosphere for grain growth study. The average grain size of the as-deposited copper films was found to be different; larger copper grains (0.6 μm) were formed on the W seed layer compared to those formed on Cu (0.2 μm). The copper films also started to recrystallize at 300 °C and grain growth occurred from 400 °C onward. Regardless of the initial grain size of the electroplated copper films, the final grain size was found to be similar on both seed materials. After 600 and 700 °C annealing, the average grain sizes became 1.00 and 1.20 μm, respectively. The driving force for grain growth is from the elimination of grain boundaries where the surface energy is being released to achieve the equilibrium state. The annealed films produced a layered micros...

A study was carried out to investigate the effect of current density and pulse waveform on the filling of line trenches and contact vias with aspect ratio of 2:1 for sub-0.25 µm device manufacturing using normal pulse plating of copper. The growth pattern of the copper films deposited using 0.05 and 0.10 A/cm2 current density gave no significant difference. Small grains were seen to have nucleated uniformly across the line trenches and via holes after 1 second of electroplating. With increasing the deposition time to 2 seconds, a slight buildup of the film thickness was observed in both trenches and vias without significant increase in the size of the copper grains. Grain growth involving the coalescence of small grains occurred after 5 seconds of plating and a further buildup in thickness and fill up of the trenches and vias occurred after 10 seconds of deposition.When the patterned wafers were plated with a pulse waveform of 3 ms on and 0.5 ms off, the filling of trenches could not be complete after 30 seconds of electroplating. A complete filling of the trenches was achieved within 30 seconds of deposition using a pulse waveform of 6 to 8 ms on and 1 to 2 ms off. When the on-period was increased above this range to 9.9 ms, voids were observed at the centre of the via holes.

Publisher Summary This chapter describes the characteristic differences in microstructure and hardness of the composite layers produced in a helium and nitrogen environments, and is characterized in terms of microstructure, layer thickness, surface cracking, and hardness. In the present study, 5 and 10 vol% of 3 μm size SiCp powders are used. Laser melting in a nitrogen environment dissolved all SiCp, and the metal matrix composite (MMC) track consisted of dendrites at the top surface followed by thread-like particles. The MMC layer produced under a helium environment resulted in a dissolution of SiCp and precipitation of TiC or partial dissolution of SiCp and agglomeration into a band. In the nitrogen environment, the dendrites are very compact after glazing at high-energy densities. The tracks glazed under a helium environment are free from surface cracking, but those produced in a pure nitrogen environment contained cracks. The melted layer thicknesses are seen to be 2 to 4 times greater than for tracks produced in a helium environment. The dendritic structures of nitride/carbonitride developed higher hardness, and the extra thermal energy released from nitride formation in the applied nitrogen environment, increased the melt temperature and the melt depth, as compared to those tracks produced using a helium environment. The microstructure produced in a helium environment is dominated by dissolution of SiCp and formation of thread-like particles. These observations suggest that cracking is related to high hardness, which in turn is associated with agglomeration of hard particles.

Copper films were electroplated on either W/TiN/Si(100) or Cu/TaN/Si(100) surfaces with copper electrolytes containing different types of acids, namely, H2SO4, HCl, HNO3, and HF. The properties of these copper films were then characterized in terms of their microstructure and electrical properties. Dense copper films were obtained from H2SO4 and HNO3-based electrolytes, which produced films consisting of small equiaxed grains with average grain sizes of 0.25 μm whereas larger grains of 0.5 μm were obtained from a HF-based electrolyte. However, a very rough Cu film with copper chloride residues was obtained from the HCl-based electrolyte. For W seeded substrates, strong 〈111〉 oriented copper films were produced while both 〈111〉 and 〈220〉 were observed as the preferred orientations of the film on Cu seeded substrates. Both H2SO4- and HNO3-based electrolytes were able to produce films with bulk resistivity as low as 1.82 μΩ cm on Cu seeded substrates. For W seed, the bulk resistivity varied between 1.92 and ...

A number of etching reagents have been appraised with a view to establishing a simple technique for distinguishing the different phases in the compound zone of nitrided irons and steels, and distinguishing the different microconstituents in the nitride alloy steels. Oberhoffer's reagent is found to be the best single etchant, and its action and that of the other etchants investigated are described.