Microstructure and mechanical properties of a 2091 AlLi alloy—I. Microstructure investigated by SAXS and TEM

The microstructure of the 2091 alloy (AlLiCuMgZr) alloy has been studied and compared to that of two simpler AlLi and AlCuMg alloys. The SAXS, in situ SAXS and TEM techniques have been used for heat treatments at room temperature and at 150°C. The time evolution of the size and of the volume fraction of the δ′ precipitates and of the Cu-rich GPB zones have been determined. The δ′ precipitates are shown to follow a classical Lifschitz-Slyosov-Wagner law. Their interfacial energy has been estimated. S and S′ precipitates have also been characterized, respectively on grain boundaries and on helical dislocations, by TEM.     

Processing,Microstructure, and Mechanical Properties of B4C ― TiB2 Particulate Sintered Composites. Part II. Fracture and Mechanical Properties

The fracture response of pressureless sintered boron carbide ceramics containing 5-25 vol.% TiB₂ phase produced via the in-situ chemical reaction between B₄C, TiO₂ and elemental carbon was studied. Both strength and fracture toughness depend on TiB₂ volume fraction, reaching their maximum values of 500 MPa and 4.6 MPa·m^1/2, respectively, at 15 vol.% TiB₂. The observed increase in strength and fracture toughness was ascribed to the interaction between the propagating crack front and local thermal mismatch stress associated with TiB₂ particles. Induced circumferencial microcracking and crack impedance are discussed as the major toughening mechanisms. Spontaneous circumferencial microcracking due to thermal mismatch stress in TiB₂ particles was found to occur when the particle size exceeds its critical value. The theoretical interpretation of spontaneous circumferencial microcracking, toughening via induced microcracking, and crack impedance was justified experimentally.     

Microstructure,Tribological Properties,and Hardness of Spray-Deposited and Warm-Rolled Al–Pb Alloys in Peripheral Regions

Powder Metallurgy and Metal Ceramics - The Al–18% Pb and Al–20% Pb alloys were processed by a rapid solidification, i.e., the spray deposition technique. The deposit in a shape of...     

Weldability and Microstructure of Nickel-Silicon Based Alloys

The NiSix based alloy typically has poor weldability due to its lower ductility. A limited amount of work has been performed on the weldability of NiSix based alloys. Therefore, the effect of heat treatment and welding parameters on weldability of the alloys, and the relationship between the weldability and microstructure were studied. The results show that the as-cast Ni-Si-Nb-B alloy （Ni 76. 5%, Si 20%, Nb 3%, and B 0. 5%） could be successfully welded after preheating at 600 ℃. The welding procedure should be performed on the alloys before any heat treatment and a preheating at 600 ℃ should be used. The fusion zone is harder than the matrix due to a large amount of 7 phase and a finer microstructure. The cracks are predominantly intergranular in heat affected zone and associated with the needle-like ）, phase. The heat treatment before welding increases the tendency of cracking in the fusion zone.     

Microstructure and Properties of Lao.7 Sr0.3 MnO3 Films Deposited on LaAlO3 （100）, （110）, and （111） Substrates

A comparative study of the crystalline structure, magnetic properties, and transport properties of LSMO films grown on （100）-, （110）-, and （111） LaAlO3（LAO） substrates was carried out. Using atomic force microscopy, round, rectangle, and dot surface morphologies were observed in （ 100）-, （ 110）-, and （ 111 ）-oriented LSMO films, respectively. Electrical and magnetic characterizations were performed on LSMO films of different orientation to provide evidence for the effect of strain on the magnetotransport properties. The （ 111 ）-oriented LSMO film has higher saturation magnetization and lower resistance compared with the （100）- and （110）-oriented LSMO films, which results from the smaller elastic deformation due to the larger elastic modulus along the 〈 111 〉 crystallographic direction.     

Microstructure and Emission Properties of Nanometer Ce-W Material

Nanometer Ce-W material was prepareo by freeze-drying and SPS. SEM and “in situ” AES were used to investigate microstructure, surface behavior and emission properties of material. Compared with micrometer material, the crystal size of nanometer material is smaller. Homogeneous microstructure and uniform distribution of cerium are found in nanometer material. The diffusion ability of Cerium becomes stronger. At high-temperature, the active layer thickens,     

Microstructure and mechanical properties of a 2091 AlLi alloy—II. Mechanical properties: Yield stress and work hardening

Mechanical properties of a 2091 AlLiCuMg (Zr) alloy are investigated together with those of simpler AlLi (Zr) and AlCuMg (Zr) model alloys. The different contributions to the yield stress are estimated from the microstructure investigated in companion Paper I. Work hardening is described using Ashby's model, but taking into account the strain localization.     

Mechanical behavior of Al−Li−SiC composites: Part I. Microstructure and tensile deformation

The microstructure and tensile properties of an 8090 Al−Li alloy reinforced with 15 vol pet SiC particles were investigated, together with those of the unreinforced alloy processed following the same route. Two different heat treatments (naturally aged at ambient temperature and artificially aged at elevated temperature to the peak strength) were chosen because they lead to very different behaviors. Special emphasis was given to the analysis of the differences and similarities in the microstructure and in the deformation and failure mechanisms between the composite and the unreinforced alloy. It was found that the dispersion of the SiC particles restrained the formation of elongated grains during extrusion and inhibited the precipitation of Al₃Li at ambient temperature. The deformation processes in the peak-aged materials were controlled by the S′ precipitates, which acted as barriers for dislocation motion and homogenized the slip. Homogeneous slip was also observed in the naturally aged composite, but not in the unreinforced alloy, where plastic deformation was concentrated in slip bands. The most notorious differences between the alloy and the composite were found in the fracture mechanisms. The naturally aged unreinforced alloy failed by transgranular shear, while the failure of the peak-aged alloy was induced by grain-boundary fracture. The fracture of the composite in both tempers was, however, precipitated by the progressive fracture of the SiC reinforcements during deformation, which led to the early failure at the onset of plastic instability.     

Study on Microstructure and Performance of Advanced Bush Strip

Therearemanykindsofbushmaterials ,suchasbabbitalloy ,copper leadalloy ,aluminum tinalloyandaluminum leadalloy .Therearisesabigdemandforthematerialusedinmotorastheautomotivein dustrydevelops .Inordertosatisfythedemandofhighspeedandlonglife ,anewbushmaterialAlSn8Si2 5Pb2 Cu0 8Cr0 2 (ASP ) [1] wasdevelopedinAmerica .Becausethedistributionsoftin ,silicon ,lead ,copperandchromiumareuniformanddisper sive ,thismaterialhasmanyadvantages ,suchasgoodantifriction ,highwearresistance ,goodfrictionc…     

Microstructure and Properties of an Advanced Nickel-base PM Superalloy

The need for nickel-base powder metallurgy （PM） superalloy turbine discs is becoming increasingly evi dent. With the eventual aim of improving thrust-to-weight ratio of aeroengines for power generation, well integration of significantly high strength, high damage tolerance and high-temperature capability would be reasonably required. An advanced PM superalloy, which was designed for applications up to 815- 8 5 0 ℃, was experimentally investigated. Emphasis was primarily put on microstructure and mechanical properties. The results indicated the measured phases in the sample were composed of γ,γ＇, MC, and Ma B2. With uniform coarse grain microstruc ture （ASTM 5-6）, the sample appeared to exhibit overwhelming superiority over the prior art materials FGH95, FGH96, FGH97 and FGH98. The dominant embodiments consisted of high tensile strength （Rm = 1000 MPa and Rp0.2 800 MPa at 850℃）, strong creep resistance （ξp 0.12% at 815 ℃/400 MPa/50 h）, and considerable stressrupture life （τ=457.4 h at 815 ℃/450 MPa）. The technical practicability of applications up to 815-850 ℃ of this alloy was conclusively proved.     

Power and conflict resolution in sibling, parent–child, and spousal negotiations.

This study used a within-family observational design to examine conflict strategies (planning, opposition) and resolutions (standoff, win-loss, compromise) across family subsystems, with an emphasis on power differences between parents and children during relatively symmetrical within-generation (spousal, sibling) and relatively asymmetrical between-generation (parent–child) dyadic interactions. Up to six dyads in 67 families (children's ages ranging from 3 to 12 years) discussed an unresolved conflict. Results revealed that within-generation discussions ended more in standoff, whereas between-generation discussions ended with more win-loss resolutions. Multilevel analyses indicated that parents engaged in more planning and opposition than children; however, they opposed more and planned less with their spouses than their children. In general, more planning and less opposition were associated with achieving resolutions rather than failing to resolve differences. Some effects were qualified by within-family differences between mothers versus fathers and older versus younger siblings, as well as between-family differences in younger siblings' age. Implications for theories of power and family relationship dynamics are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Report by the… ; purposes, standards, and procedures.

"The American Board for Psychological Services was incorporated to accomplish one fundamental purpose: to serve the public interests by providing a directory of agencies judged to be capable of providing competent psychological services to the public." Means by which ABPS intends to achieve its functions, the definition of "psychological service," criteria for evaluation of psychological services, evaluation procedures, means of appeal from ABPS judgments, reevaluations, and current fees and charges of ABPS, are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Comment on the Article “Initial Reactions at the Electrodes of the FFC-Cambridge Process in Molten CaCl2 to Produce Ti” by P.S. Lai,M.L. Hu,Z.F. Qu,L.Z. Gao,C.G. Bai,T.X. Wang,S.F. Zhang,and G.B. Qiu

Metallurgical and Materials Transactions B -