Apparatus and method for making powder from a metallic melt by atomizing the melt to form droplets and reacting the droplets downstream of the atomizing location with a reactive gas. The droplets are reacted with the gas at a temperature where a solidified exterior surface is formed thereon and where a protective refractory barrier layer (reaction layer) is formed whose penetration into the droplets is limited by the presence of the solidified surface so as to avoid selective reduction of key reactive alloyants needed to achieve desired powder end use properties. The barrier layer protects the reactive powder particles from environmental constituents such as air and water in the liquid or vapor form during subsequent fabrication of the powder to end-use shapes and during use in the intended service environment.
A method of making dispersion-strengthened alloy particles involves melting analloy having a corrosion and/ or oxidation resistance-imparting alloying element, adispersoid-forming element, and a matrix metal wherein the dispersoid-forming element exhibits a greater tendency to react with a reactive species acquired from an atomizing gas than does the alloying element. The melted alloy is atomized with the atomizing gas including the reactive species to form atomized particles so that the reactive species is (a) dissolved in solid solution to a depth below the surface of atomized particles and/or (b) reacted with the dispersoid-forming element to form dispersoids in the atomized particles to a depth below the surface of said atomized particles. The atomized alloy particles are solidified as solidified alloy particles or as a solidified deposit of alloy particles. Bodies made from the dispersion strengthened alloy particles, deposit thereof, exhibit enhanced fatigue and creep
A method of making dispersion-strengthened alloy particles involves melting an alloy having a corrosion and/ or oxidation resistance-imparting alloying element, a dispersoid-forming element, and a matrix metal wherein the dispersoid-forming element exhibits a greater tendency to react with a reactive species acquired from an atomizing gas than does the alloying element. The melted alloy is atomized with the atomizing gas including the reactive species to form atomized particles so that the reactive species is (a) dissolved in solid solution to a depth below the surface of atomized particles and/or (b) reacted with the dispersoid-forming element to form dispersoids in the atomized particles to a depth below the surface of said atomized particles. The atomized alloy particles are solidified as solidified alloy particles or as a solidified deposit of alloy particles. Bodies made from the dispersion strengthened alloy particles, deposit thereof, exhibit enhanced fatigue and creep
were sequentially enrolled. Patients with COPD, referred from primary care, had regular consultations in an outpatient clinic specific for COPD patients, localized inside the hospital. The control group consisted of volunteers recruited from the same hospital, who visited other outpatients’ clinics and had normal spirometry. Most of these volunteers had regular appointments for checkup and did not have any comorbidity. We only included never or former smokers with an abstinence time of more than 6 months. COPD patients with an episode of exacerbation in the last 4 weeks were excluded. We also excluded patients and controls diagnosed with asthma or cancer in the last 5 years; current or former smokers with an abstinence time of less than 6 months; suspected diagnosis of acute inflammatory or infectious disease, surgery, or trauma in the last 30 days; diabetes; heart failure; chronic renal failure; pregnancy; stroke; and ischemic heart disease. The Ethics Committee from Hospital de Clínicas de Porto Alegre approved the study, and all subjects gave written informed consent to participate in the study.
K. The aqueous solutions of LA with various de- sired concentrations were made by dissolving liquid LA in Millipore Milli-Q deionized water (MERCK Millipore ltration). All the aqueous solutions were homogenized and uniformly mixed. The organic phase of volume 10 mL was made of various extractants (TOA, TDDA, and Aliquat336), organic solvents, and environmentally benign green solvents. Both of the phases at dierent phase ratios were intermixed in an Erlenmeyer or conical ask and shaken at a stirring speed of 100 rpm for two hours to gain the extraction equilibrium. Then, the solution was placed in the test tubes for settling and exact phase separation of both phases. After the settling of solution, two phases (organic phase (top phase) and aqueous phase (bottom phase)) were formed, and the concentration of LA in the aqueous phase was determined through acid-base titration and reconrmed by a colorimetric method by using UV/VIS- spectrophotometer (model DR 5000 HACH, USA) . The organic phase concentration was calculated by the materials balance. The various experimental conditions and holding values for LA reactive extraction are shown in Table 1.
Based on above results by TEM and EDS (refer to Fig. 5), and discussion, we can draw a schematic diagram of breakdown/remove mechanism of oxide ﬁlm at interfaces between particles in Al-Mg alloy specimens prepared by PECS process, as shown in Fig. 6. There are two processes to remove oxide ﬁlm in Al-Mg alloy specimens in PECS process, namely, mechanical breakdown by plastic deforma- tion of powder particles under loading pressure and deoxi- dization by Mg with oxide ﬁlm. Based on temperature range of the formation products in the deoxidization, it has been deduced that the temperature at the contact interface between powder particles is higher than the average temperature for Al-Mg alloy specimens during PECS process. 20) Due to a
provides new and improved methods for making chalcogenide compounds, including, but not limited to, non- protonated sulfide, selenide and telluridecompounds. In one embodiment, the proton conductivity of the compounds is between about 10 −8 S/cm and 10 −1 S/cm within a temperature range of between about −50 and 500° C.
But with the rise of neoliberalism during the 1970s, the focus of economic theory and policy shifted to the monetary causes of inflation and the efficiency and welfare benefits associated with free markets (Friedman, 1977). There was a reversion to the pre- Keynesian view that rather than being a systemic problem, the responsibility for unemployment and poverty lies with the jobless and the poor. Since 1979, macroeconomic policy has been dominated by attempts to control inflation by monetary means whilst responsibility for increasing employment has been delegated to market forces. Trade unions have been weakened, legal control of labour standards relaxed, out-of-work benefits reduced and subject to more onerous conditions, and wage subsidisation has been introduced with the express purpose of making the labour market more ‘flexible’. Concurrently, other markets have been deregulated, restrictions on the money supply have been lifted, large sections of the public sector have been privatised and taxes on the rich have been cut to encourage enterprise.
Figure 49 shows the HP specimen lattice parameters calculated by XRD and Vegard’s Law from the powder compositions (Table 3). The similar lattice constants of pure W and Mo, 3.16 Å and 3.15 Å, respectively, result in similar lattice constants in the consolidated specimens. Conversely, the lattice constant of Cr is 2.88 Å and results in much lower lattice constants as suggested by Vegard’s Law (Figure 49). All of the specimen powders have larger lattice parameters than suggested by Vegard’s Law and the consolidated specimens deviated even further from Vegard’s Law. Structural relaxation is seen with increased consolidated temperature; the lattice parameter increases. This relaxation is expected due to the induced lattice strain attributed to the high-energy ball milling. Previous studies have reported the expansion over-predicted lattice constants in annealed WCr alloys; however, the cause of the deviation has not been determined. 134 Deviation from Vegard’s Law has been reported in several studies and Vegard’s Law is now considered more of a generalization. 135, 136, 137, 138, 139 Lattice-parameter variation from Vegard’s Law may be attributed to changes in the crystal structure. 140 In this study, all lattice parameters were calculated from bcc peaks, (200) and (211), though
ferrofluids such as doping for technological materials, dynamic sealing, damping, heat dissipation , as a working body in tilt sensors , improving the efficiency of a PVT (photovoltaic unit) system in a solar cell , lubrication , and many more. However, they have not been commercialized yet at a great level. The primary reason for this is the lack of stability in ferrofluids against agglomeration and gravitational sedimentation of the magnetic nanoparticles. There are different factors that determine the stability of ferrofluids; some of them are: type and size of the magnetic nanoparticles, type of surfactant, type of carrier fluid, method of coating, etc. The factors have been discussed in detail in the following chapters.
shown in the ﬁgure, spherical bright contrasts are distributed among the ﬁlm at 100 nm in depth, which indicates voids formation inside of matrix. Since matrix phase, the region outside of voids, still maintain amorphous matrix, Ar- implantation causes atom mixing inside of Zr-Cu without crystallization process. Accounting for the fact that solubility of 5 at%Ar in amorphous matrix by XPS, large parts of implanted Ar makes aggregation in Zr-Cu because of its inert nature. It should be mentioned that the dosed amounts of Ar in present experiments corresponds to the average atomic concentration about 30 at%Ar in Zr-Cu ﬁlm, so that the same amounts of Zr and Cu atoms should be replaced by penetrated Ar atom from its original lattice site. The volume fraction calculated from the projected area of circular voids amounts to 30% in total thickness of Zr-Cu ﬁlm. In literature, 17,18)
has also economic problems of an increase in processing costs for changing TiNi ingot into powder. In this study, the microstructural and mechanical properties of TiNi alloy with pre-mixed powder of pure Ti powder and pure Ni powder is investigated, which are easy to control TiNi composition ra- tio and inexpensive materials in comparison with TiNi alloy powder. The mechanism of high-strengthened the extruded and heat-treated TiNi alloys by sintering the mixture of TiNi pre-mixed powder with titanium dioxide (TiO 2 ) particles is
P/M aluminium alloys can be improved without recourse to hot working or master alloypowders if their design is based on an understanding of the underlying sintering processes and the characteristics of an ideal liquid phase sintering system . However, this idea can be applied to the design of suitable aluminium alloys for the fabrication of parts in SLS process with a view to ensuring that the oxide phase of the aluminium powders is disrupted in order to make allowance for effective inter-particle bonding/melting across the layers so as to achieve the production of full density parts. This entails the determination of the appropriate chemical composition of aluminium alloys that make allowance in their thermal cycle for the transient nature of the adequate liquid phase during SLS in addition to the alloying elements contained in them effectively disrupting the surface oxide of the aluminium powder. Furthermore, designing such SLS processable aluminium alloys necessitates that the mechanism of disruption of their surface oxide film need to be understood. Therefore, an investigation is necessary to ascertain if alloys of the same composition as those employed in the press and sinter technique could give equivalent or a better sintering response during SLS without the application of hot working processes. If this is not the case, alloys that would give desirable response to SLS need to be designed.
where h, k, l are Miller indices. the Nelson–Riley method was used to minimize errors caused by aberration of 2θ variation and the lattice parameter ‘a’ of TaC was calculated for at least three peaks, using Equation (3) .
From the point of the dependent variable of surface roughness and tool wear, it was observed that the parameter of the depth of cut became a less effective factor in the contribution of the dry machining. On the other hand, two cutting parameters which are cutting speed and feed rate were an extremely superior factor in order to generate the lower value of surface roughness and improved tool wear in the dry machining. High and low values in respective cutting speed and feed rate are important in managing the reduction of built-up edge (BUE), thus reducing the shear strength as well as result in worsening the surface quality as claimed by Yi et al.  after end milling aluminum alloy 6061-T6. However, it promotes the detrimental effect towards the tool wear.