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

Mechanical alloying (MA) is a solid-state powder processng technique involving repeated welding, fracturing, and rewelding of powder particles in a high-energy ball mill. Originally developed to produce oxide-dispersion strengthened (ODS) nickel- and iron-base superalloys for applications in the aerospace industry, MA has now been shown to be capable of synthesizing a variety of equilibrium and non-equilibrium alloy phases starting from blended elemental or prealloyed powders. The non-equilibrium phases synthesized include supersaturated solid solutions, metastable crystalline and quasicrystalline phases, nanostructures, and amorphous alloys. Recent advances in these areas and also on disordering of ordered intermetallics and mechanochemical synthesis of materials have been critically reviewed after discussing the process and process variables involved in MA. The often vexing problem of powder contamination has been analyzed and methods have been suggested to avoid/minimize it. The present understanding of the modeling of the MA process has also been discussed. The present and potential applications of MA are described. Wherever possible, comparisons have been made on the product phases obtained by MA with those of rapid solidification processing, another non-equilibrium processing technique.

Mechanical Alloying And Milling

ion. The oxidative addition mechanism was originally proposed22i because of the lack of a strong rate dependence on polar factors and on the acidity of the medium. Later, however, the electrophilic substitution mechanism also was proposed. Recently, the oxidative addition mechanism was confirmed by investigations into the decomposition and protonolysis of alkylplatinum complexes, which are the reverse of alkane activation. There are two routes which operate in the decomposition of the dimethylplatinum(IV) complex Cs2Pt(CH3)2Cl4. The first route leads to chloride-induced reductive elimination and produces methyl chloride and methane. The second route leads to the formation of ethane. There is strong kinetic evidence that the ethane is produced by the decomposition of an ethylhydridoplatinum(IV) complex formed from the initial dimethylplatinum(IV) complex. In D2O-DCl, the ethane which is formed contains several D atoms and has practically the same multiple exchange parameter and distribution as does an ethane which has undergone platinum(II)-catalyzed H-D exchange with D2O. Moreover, ethyl chloride is formed competitively with H-D exchange in the presence of platinum(IV). From the principle of microscopic reversibility it follows that the same ethylhydridoplatinum(IV) complex is the intermediate in the reaction of ethane with platinum(II). Important results were obtained by Labinger and Bercaw62c in the investigation of the protonolysis mechanism of several alkylplatinum(II) complexes at low temperatures. These reactions are important because they could model the microscopic reverse of C-H activation by platinum(II) complexes. Alkylhydridoplatinum(IV) complexes were observed as intermediates in certain cases, such as when the complex (tmeda)Pt(CH2Ph)Cl or (tmeda)PtMe2 (tmeda ) N,N,N′,N′-tetramethylenediamine) was treated with HCl in CD2Cl2 or CD3OD, respectively. In some cases H-D exchange took place between the methyl groups on platinum and the, CD3OD prior to methane loss. On the basis of the kinetic results, a common mechanism was proposed to operate in all the reactions: (1) protonation of Pt(II) to generate an alkylhydridoplatinum(IV) intermediate, (2) dissociation of solvent or chloride to generate a cationic, fivecoordinate platinum(IV) species, (3) reductive C-H bond formation, producing a platinum(II) alkane σ-complex, and (4) loss of the alkane either through an associative or dissociative substitution pathway. These results implicate the presence of both alkane σ-complexes and alkylhydridoplatinum(IV) complexes as intermediates in the Pt(II)-induced C-H activation reactions. Thus, the first step in the alkane activation reaction is formation of a σ-complex with the alkane, which then undergoes oxidative addition to produce an alkylhydrido complex. Reversible interconversion of these intermediates, together with reversible deprotonation of the alkylhydridoplatinum(IV) complexes, leads to multiple H-D exchange

Activation of c-h bonds by metal complexes

Hydrogen Production by Molecular Photocatalysis

Transition metal catalyzed oxidative functionalization of carbon-hydrogen bonds

Modified version of Monkman-Grant equation for Gr.91 by incorporating “strain to minimum creep rate” parameter

PROBLEM TO BE SOLVED: To improve a high-temperature creep property in a temperature range of 650°C or higher of a martensitic heat-resistant steel, enable the higher high- temperature creep property to be kept for a long time, make the thermal expansion characteristics in the temperature range of 650°C or higher to be low, and improve the thermal fatigue characteristics. SOLUTION: In the martensitic heat-resistant steel having a martensite single- phase structure at room temperature, in which carbides do not precipitate, a structure in the temperature range of 650°C or higher has two-phases comprising an austenitic phase of a parent phase and a finely dispersed and precipitated intermetallic compound phase, or three phases comprising the austenitic phase of the parent phase, a ferritic phase and the finely dispersed and precipitated intermetallic compound phase. COPYRIGHT: (C)2003,JPO

Two-phases or three-phases structure in temperature range of 650°c or higher of martensitic heat-resistant steel

The corrosion behavior of nickel base heat resisting alloys is investigated in steam at 800°C and 40atm, simulating the superheated steam of the nuclear steelmaking system. The alloys tested are five new alloys developed for the nuclear steelmaking system and one commercial alloy Inconel 617.A protective surface oxide scale, consisting of Cr2O3 mainly and of MnCr2O4, forms on the alloys except Inconel 617. Internal oxides, consisting of Al and Ti oxides, also form in the alloys containing Al. For Inconel 617, nodular oxides, consisting of NiO in the outer region and Cr internal oxides in the inner region, form in addition to Cr2O3 and MnCr2O4 after 1000h. No decarburization occurs in each alloy.The effect of alloy compositions on the corrosion behavior is discussed. The rate of Cr depletion resulting from the formation of Cr2O3-rich scale is found to be influenced by the presence of MnCr2O4 layer outside the Cr2O3 scale, and is described by a parabolic rate law for the alloys with thin MnCr2O4 layer and by a cubic rate law for the alloys with thick MnCr2O4 layer. Al and Ti, which are reactive more than Cr, are found to improve a resistance to spalling of the Cr2O3-rich scale, through a key-on eject by the internal oxides and by the enrichment of Ti oxides at the Cr2O3 scale/alloy interface.

Corrosion Behavior of Nickel Base Heat Resisting Alloys for Nuclear Steelmaking System in High-temperature Steam

PROBLEM TO BE SOLVED: To provide an MX carbonitride precipitation-strengthened heat-resistant steel which is a heat-resistant steel utilizing a strengthening mechanism by the precipitation of carbonitride and in which the high-temperature creep strength at 600 to 650°C is improved. SOLUTION: The MX carbonitride precipitation-strengthened heat-resistant steel utilizes a strengthening mechanism by the precipitation of MX carbonitride and has the improved high-temperature creep strength at 600 to 650°C, wherein the content of a compound MX carbonitride comprising NbC (TaC) and VN is restricted to below 30% by weight with respect to the entire precipitated MX carbonitride. COPYRIGHT: (C)2007,JPO&INPIT

Mx carbonitride precipitation-strengthened heat-resistant steel

DATA SHEETS ON THE ELEVATED-TEMPERATURE PROPERTIES OF NICKEL BASED 21Cr-18Fe-9Mo SUPERALLOY PLATE (JIS NW 6002) AND NICKEL BASED 21Cr-18Fe-9Mo SUPERALLOY BARS (JIS NW 6002) FOR GAS TURBINE COCMPONENTS

Fujio Abe

Papers

Modified version of Monkman-Grant equation for Gr.91 by incorporating “strain to minimum creep rate” parameter

Two-phases or three-phases structure in temperature range of 650°c or higher of martensitic heat-resistant steel

Corrosion Behavior of Nickel Base Heat Resisting Alloys for Nuclear Steelmaking System in High-temperature Steam

Mx carbonitride precipitation-strengthened heat-resistant steel

DATA SHEETS ON THE ELEVATED-TEMPERATURE PROPERTIES OF NICKEL BASED 21Cr-18Fe-9Mo SUPERALLOY PLATE (JIS NW 6002) AND NICKEL BASED 21Cr-18Fe-9Mo SUPERALLOY BARS (JIS NW 6002) FOR GAS TURBINE COCMPONENTS