Intercellular Phase Research Articles

The compound AST-003 could effectively promote apoptosis of renal cell carcinoma cells in vitro.

BackgroundThe toxicity of Sunitinib limits its clinical application. A new compound AST-003 was designed and synthesized based on the structure of Sunitinib, and previous study has confirmed that AST-003 has the same efficacy and less toxicity as Sunitinib. We conducted this study to further verify the effect of AST-003 on renal cell carcinoma (RCC) cells in vitro and its mechanism.MethodsFive RCC cell lines, A498, 786-0, SW-13, Caki-1 and ACHN, were used. Cells were treated with different concentrations of AST-003, and the effect of AST-003 on cell viability was detected by MTT assay and IC50 was determined. Blank control group and AST-003 group were set to evaluate the effect of AST-003 on cell apoptosis and cell cycle. The effect of AST-003 on cell protein expression was detected by western blot.ResultsAfter treatment with AST-003, the viability of the above five RCC cells was significantly inhibited. The IC50 of AST-003 on A498, 786-0, SW-13, Caki-1 and ACHN were 7.396, 6.592, 3.803, 12.05 and 3.422 µmol/L, respectively. Compared with the blank control group, the apoptotic rates were 52.37% and 13.34% in A498 cells (P<0.001), 59.23% and 6.66% in 786-0 cells (P<0.001), 45.67% and 4.19% in SW13 cells (P<0.001), 51.67% and 2.33% in Caki-1 cells (P<0.001), 55.40% and 5.50% in ACHN cells (P<0.001). Flow cytometry revealed that the proportion of cells in G0/G1 phase was significantly increased and the proportion of cells in S phase was significantly decreased in AST-003 group compared with blank control group, suggesting that AST-003 could block cells in G0/G1 phase. Western blot indicated that AST-003 could induce the up-regulation of the protein expression levels of apoptotic genes Caspase3, Caspase8, Caspase9, Bax and tumor suppressor p53, and inhibit the phosphorylation of STAT3, mTOR, AMPK and ERK, as well as the expression of Bcl-2, MKK, MKKK, c-jun and Ras proteins.ConclusionsWe found that AST-003 could effectively promote the apoptosis of RCC cells in vitro and block the cells in the intercellular phase, and its mechanism was similar to that of Sunitinib, suggesting that AST-003 has the value for further research.

Effects of cellular growth on fatigue life of directionally solidified hypoeutectic Al-Fe Alloys

Al-Fe hypoeutectic alloys are a family of casting alloys characterized by cell growth, low cost and appreciable formability. It is well known that fatigue strength is a requirement of prime importance considering the nature of load typically observed during operations involving the risers used in oil extraction. The aim of this study is to examine the influence of cell size and its intercellular phase distribution on the fatigue life (Nf) of the directionally solidified Al-0.5, 1.0 and 1.5wt% Fe alloys. A water-cooled vertical upward unidirectional solidification system was used to provide the castings. Microscopy light and SEM microscopy were used. It was found that fatigue life decreases as cell spacing (λ c) increases. Smaller cell spacing allows a homogeneous distribution of Al-Fe fibers to happen within the intercellular regions, which tends to improve the mentioned fatigue property. Hall-Petch type correlations [Nf= Nf0+A(λc -1/2)-B(λc -1); where A and B are constants] seems to be able to encompass the fatigue life variation along the Al-Fe alloys.

Preinspiratory calcium rise in putative pre‐Bötzinger complex astrocytes

The neural inspiratory activity originates from a ventrolateral medullary region called the pre-Bötzinger complex (preBötC), yet the mechanism underlying respiratory rhythmogenesis is not completely understood. Recently, the role of not only neurons but astrocytes in the central respiratory control has attracted considerable attention. Here we report our discovery that an intracellular calcium rise in a subset of putative astrocytes precedes inspiratory neuronal firing in rhythmically active slices. Functional calcium imaging from hundreds of preBötC cells revealed that a subset of putative astrocytes exhibited rhythmic calcium elevations preceding inspiratory neuronal activity with a time lag of approximately 2 s. These preinspiratory putative astrocytes maintained their rhythmic activities even during the blockade of neuronal activity with tetrodotoxin, whereas the rhythm frequency was lowered and the intercellular phases of these rhythms were decoupled. In addition, optogenetic stimulation of preBötC putative astrocytes induced firing of inspiratory neurons. These findings raise the possibility that astrocytes in the preBötC are actively involved in respiratory rhythm generation in rhythmically active slices.

Rutaceae sampled from Germany, Malta, and Mallorca (Spain) are associated with AMF clustering with Glomus hoi Berch &amp; Trappe

Six Rutaceae species collected from natural habitats (Malta, Mallorca (Spain), and Tenerife (Spain)) and the Botanical Garden in Marburg were examined with respect to mycorrhizal structures and fungal identity. All species have the same gross colonization pattern of arbuscular mycorrhiza (AM) with distinct intracellular and intercellular phases but show remarkable differences in details, especially in terms of the extent of the intracellular phase. The associated AM fungi, identified using molecular methods, cluster together with Glomus hoi Berch & Trappe, although the plants were collected from very distant locations.

Diffusion and creep of Sr 3(Ca 1.18Nb 1.82)O 9− δ mixed Perovskite fabricated by melt processing

Compressive creep tests of Sr 3(Ca 1.18Nb 1.82)O 9− δ mixed Perovskite fabricated by melt processing were conducted in Ar and air to determine the deformation rate and to estimate the diffusion coefficient. At 1300–1350 °C, the steady-state strain rate ( ε˙) could be expressed as ε · = A σ 1.9 ± 0.2 exp ⁡ [ ( − 670 ± 94 kJ / mole ) / R T ] where A is a constant, σ is the steady-state stress, R is the universal gas constant, and T is the absolute temperature. The data and microstructural observations indicated that the mechanism that controls plasticity is grain rotation associated with redistribution of the intercellular phase, accommodated by cell coalescence, due to diffusion and dislocations.

Fabrication and Properties of High Temperature Proton Conducting Perovskites

High temperature protonic conductors (HTPC) were fabricated by solid-state sintering and by melt processing by laser-heated floating zone method. Several families of compositions were selected: SrCe1-xMxO3-δ (with M: Zr and Y; x = 0.1, 0.2), BaCe1-xMxO3-δ (with Yb, Ca and Y; x = 0.05, 0.2), Sr3Ca1.18Nb1.82O9-δ, SrZr0.8Y0.2O3-δ and SrTi0.95Sc0.05O3-δ. Their mechanical properties have been studied by compression test at constant load and constant compression rate. As produced directionally solidified materials presented a unique microstructure consisting of strongly textured cells with an intercellular phase. The cells have a crystalline Pnma structure. The relation between the processing, dopants, microstructure and mechanical properties is discussed. Understanding of plasticity is important to determine the ultimate component performance, and because its direct relationship to processing and transport. The high temperature mechanical properties of melt grown crystals are superior to the mechanical properties of polycrystals.

Notochordal Cell Produce and Assemble Extracellular Matrix in a Distinct Manner, Which May Be Responsible for the Maintenance of Healthy Nucleus Pulposus

Analysis of proteoglycan synthesis, distribution and assembly of notochordal cells and small nucleus pulposus cells embedded in alginate beads and cultured in presence of [S]-Na2SO4. To determine whether the degeneration of the nucleus pulposus of the intervertebral disc is associated with a change in the cell phenotype. The loss of the notochordal cell from the nucleus pulposus is associated with ageing and disc degeneration. The reduction in their numbers after birth in humans and in the chondrodystrophoid dog has been suggested to result from cell death and replacement or differentiation by chondrocytes. The almost total disappearance of the notochordal cells in the nucleus pulposus correlates with early degenerative changes in the disc and a concomitant reduction in proteoglycan content, increased collagen, and loss of water content. The basic mechanism of this accelerated degeneration with ageing is poorly understood. Nucleus pulposus and anulus fibrosus cells were isolated from the lumbar intervertebral discs of chondrodystrophoid and nonchondrodystrophoid dogs. The cells from the nucleus pulposus were further separated by size into notochordal cells and small nucleus pulposus cells. Cells were embedded in alginate beads and cultured in the presence of [S]-Na2SO4 to measure proteoglycan size, rate of synthesis, and distribution into the pericellular and intercellular compartments. Large notochordal cells in the nucleus pulposus of chondrodystrophoid dogs formed 13% of the cell population in young dogs and fell to 0.4% in adults, whereas they were the predominant cell type in the nonchondrodystrophoid dogs at all ages. These cells were capable of 1.5-fold greater rate of synthesis of proteoglycans than the small nucleus pulpous cells. Proteoglycans secreted by the large cells were evenly distributed between the pericellular and intercellular compartments,whereas the small cells distributed 3-fold more proteoglycan into the intercellular phase. By size exclusion chromatography, the proteoglycans synthesized by the small cells of the chondrodystrophoid dogs formed large-size aggregates (Kav = 0.1) within the pericellular region, which then moved to the intercellular region over 5 to 10 days. In contrast, proteoglycans secreted by the notochordal cells were capable of rapid migration to the intercellular phase before assembly into large-sized aggregates. The ability to form aggregates was independent of age of the animal. Our model shows that a change in intervertebral disc cell phenotype correlates with the grade of disc degeneration and that the notochordal cells synthesize proteoglycans, which exhibit delayed aggregation than those synthesized by the small nucleus pulposus cells. This implies that the cell type composition of the nucleus pulposus of the chondrodystrophoid and nonchondrodystrophoid dogs produces an extracellular matrix that is assembled in a distinct manner, which may affect tissue integrity.

Investigation of a directionally solidified NiAl/Cr(Mo) composite alloyed with Hf

A NiAl/Cr(Mo) composite alloyed with Hf was directionally solidified under a Ar atmosphere in Al2O3-SiO2 mold by the standard Bridgman technique. The as-grown composite was composed of NiAl matrix, lamellar Cr(Mo), and semicontinuously distributed Ni2AlHf. The G phase (Ni16Hf6Si7) formed in the presence of Si, which was a contamination resulting from the ceramic mold. The interfaces were atomically flat with no transition layer. After hot isostatic pressing (hipping) and aging treatment, the G phase completely disappeared and the amount of intercellular Ni2AlHf phase was partially reduced. The compressive yield stress and tensile strength of the composite were higher than those of many NiAl-based alloys. Embrittlement existed at high temperatures, induced by hipping and aging. The effect of the G phase and Heusler phase on the mechanical property of the composite was also discussed.

Expression and secretion of an alpha-amylase gene from a native strain of Bacillus licheniformis in Escherichia coli by T7 promoter and putative signal peptide of the gene.

The gene encoding a hyperthermostable alpha-amylase from a Bacillus licheniformis native strain was cloned in pET24d transcription vector containing T7 promoter, and expressed in Escherichia coli BL21(DE3) cells. Having confirmed the alpha-amylase activity through activity staining method on SDS-PAGE gel, the yields of production were determined in two separated intra and inter-cellular phases and compared using enzymatic assay methods. Extracellular production of the active recombinant enzyme implies the recognition of the putative signal peptide of this Bacillus sp. by E. coli secretory system. This may be because of the amino acid sequence of this signal peptide which covers all the structural parameters of a standard signal peptide processed by Lep B, the major signal peptidase in E. coli secretory system. This study recommends the use of this signal peptide for extracellular production of other foreign proteins in E. coli.

Micromagnetic simulation of the pinning and depinning process in permanent magnets

We have studied the pinning of magnetic domain walls on a simplified model of the cell structure of Sm(Co,Fe,Cu,Zr)/sub z/ precipitation hardened magnets. The pinning field strongly depends on the thickness of the intercellular phase if it is smaller than the domain wall width. Its maximum value has been verified with a one-dimensional analytical model. The cell structure plays an important role in the depinning process and it has been found that the pinning field depends linearly on the relative thickness of the intercellular phase. This behavior is universal for attractive and repulsive pinning.

Micromagnetic three-dimensional simulation of the pinning field in high temperature Sm(Co,Fe,Cu,Zr)z magnets

We have investigated domain wall pinning in Sm(Co,Fe,Cu,Zr)z based magnets with 3D micromagnetic simulations using a hybrid finite element/boundary element method. Transmission electron micrographs of magnets with Sm2(Co,Fe)17 matrix and Sm(Co,Cu)5−7 precipitation phases were used to model the cellular microstructure. The pinning field was investigated for varying thickness of the intercellular phase.

Micromagnetic simulation of domain wall pinning in Sm(Co,Fe,Cu,Zr) z magnets

Domain wall pinning in Sm(Co,Fe,Cu,Zr) z based magnets was investigated with 3D-micromagnetic simulations. The pinning effect was studied for varying thickness of the intercellular phase at constant cell size. The simulations showed a complete loss of the pinning effect for a very thin and very thick cell boundary phase. In the proper region the pinning field was calculated for varying anisotropy constant.

Microstructures and their stability in rapidly solidified Al-Fe-(V, Si) alloy powders

Microstructures and their stability in as-atomised Al-6.5Fe-1.5V and Al-6.5Fe-1.5V-1.7Si powders have been investigated using transmission electron microscopy (TEM) equipped with energy dispersive X-ray spectroscopy (EDXS), scanning electron microscopy (SEM), X-ray diffraction (XRD) and differential scanning calorimetry (DSC) techniques. It was observed that microstructures of the as-atomised powder particles showed a close relationship with powder particle sizes. The as-atomised powders exhibited three types of microstructures, namely 'zone A', 'zone B' and 'zone C'. The 'zone A' type microstructure consisted of very fine and homogeneous distributed precipitates in the α-Al matrix. The 'zone B' microstructure represented the regions consisting of microcellular structures whereas the 'zone C' microstructure represented the regions consisting of coarse cellular structures and globular quasi-crystalline phase particles. Fine powder particles exhibited both 'zone A' and 'zone B' microstructures. The size of 'zone A' decreased with increasing powder particle sizes. The intercellular phases in 'zone B' of both Al-Fe-V and Al-Fe-V-Si were very fine, randomly oriented microquasi-crystalline icosahedral particles. Microstructures of coarse powder particles exhibited both 'zone B' and 'zone C'. The intercellular phases in 'zone C' of Al-Fe-V powders could be Al6Fe, whereas in Al-Fe-V-Si powders they were probably silicide phase. Formation of powder microstructures may be explained by the interactions between the growing α-Al fronts with the freely dispersed, primary phase particles or the solute micro-segregation. Studies using DSC techniques have revealed the microstructural stability of as-atomised powders. There were three DSC exotherms observed in the as-atomised Al-Fe-V powders. The 'zone A' was stable at elevated temperatures and the exotherm peak corresponding to the transformation reactions occurring in 'zone A' was at 360°C. The exotherm peak, which might correspond to the transformation of the globular clusters of microquasi-crystalline icosahedral phase to single-phase icosahedral particles, was at 450°C. The exotherm peak, which may correspond to the formation of Al13Fe4 and Al45(V, Fe)7 phases, was at 500°C. In the as-atomised Al-Fe-V-Si powders, only one exotherm was observed with a peak at 400°C. This exotherm may correspond to precipitation of silicide phase particles.

Structural diversity in (vesicular)-arbuscular mycorrhizal symbioses.

This review describes diversity in the structure of (vesicular)-arbuscutar (VA) mycorrhizas, i.e. endomycorrhizas formed by Glomalean fungi. In particular, we consider the extent in the plant kingdom of the two classes first described by Gallaud (1905). These are: (1) the Arum-type, defined on the basis of an extensive intercellular phase of hyphai growth in the root cortex and development of terminal arbuscules on intracellular hyphai branches; (2) the Paris-type, defined by the absence of the intercellular phase and presence of extensive intracellular hyphai coils. Arbuscules are intercalary structures on the coils. However, there have been many reports that in Paris-types arbuscules are relatively few in numbers, small, or absent altogether. A survey of the literature has revealed that Paris-types occur more frequently in the plant kingdom than Arum-types and predominate in ferns, gymnosperms and many wild angiosperms. The cultivated herbs that are the subject of much experimental work are mostly Arum-types. Although evidence is still limited, there are differences at the family level. In 41 angiosperm families there are records of only Poris-type VA mycorrhizas and in 30 families records of only Arum-types. Another 21 families have examples of both classes, or intermediates between them. Accordingly, we consider whether the original division into two classes is still useful. We conclude that it is when considering the physiology of the symbiosis and especially the issue of whether different fungus/host interfaces have specialized roles in transfer of inorganic nutrients and organic carbon between the partners, if there is no such specialization between hyphai coils and arbuscules, then the latter might not be necessary1 for the function of Paris-types. This would account for reports of the infrequency or absence of arbuscules in this class. The control exerted on structures by the genomes of host and fungus, and possible reasons (anatomical and physiological) for the existence of the VA mycorrhizal structures, are discussed. The presence or absence of extensive intercellular spaces and differences in the wall structure of cortical cells might be particularly important in determining which type of VA mycorrhiza is formed. CONTENTS Summary 373 I. Introduction: Arum-types and Pom-types 374 II. Possible functional implications 375 III. Extent of the two classes in the plant kingdom 377 IV. Is the distinction between classes useful? 383 V. The structural basis 383 VI. The role of the fungal genome 384 VII. Physiology revisited 384 VIII. Conclusions 385 Acknowledgements 386 References 386.

Effect of silicon-phase on tension-compression extra-long fatigue properties of AlSi eutectic alloys: Murakami, Y., Ohyama, K., Ikeda, H., Takafuji, T. and Kobavashi, H. J. Soc. Mater. Sci. Jpn. (1995) 44 (497), 194–200

The microstructure and annealing behavior of a rapidly solidified Al-5.10Si-1.00Ti-0.70Pb (wt.%) alloy have been examined. As the cooling rates were increased from 10 to 106K/s, the dendritic structures of α-Al were replaced in order by cellular and microcellular structures; the interdendritic or intercellular phases changed from prolonged sheets into discrete rounded particles and from several phases enriched in Si, Ti, Pb, Fe, or P into a single second Pb phase. At the cooling rate of 106K/s, approximately 5.0 wt.% Si and 1.0 wt.% Ti were trapped in the α-Al microcells, whereas only the dispersed Pb particles were observed at the cell boundaries and had an epitaxial cube-cube orientation relation with α-Al matrix. The as-solidified microstructure obtained at the cooling rate of 106K/s has been found to be stable up to 450 °C for 5 h. After annealing at 450 °C for 100 h, a high volume fraction of finely dispersed phases was observed. These dispersed phases are thought to be very important in raising the room- and elevated-temperature performance and wear-resistance capability of the alloy. The precipitation characteristics are thought to result mainly from the effect of the element Ti.

Corrections

HomeCirculation ResearchVol. 79, No. 6Corrections Free AccessResearch ArticleDownload EPUBAboutView EPUBSections ToolsAdd to favoritesDownload citationsTrack citationsPermissions ShareShare onFacebookTwitterLinked InMendeleyReddit Jump toFree AccessResearch ArticleDownload EPUBCorrections Originally published1 Dec 1996https://doi.org/10.1161/01.RES.79.6.1218Circulation Research. 1996;79:1218In the article by Ying et al, “Ca2+ waves in lung capillary endothelium” (Circ Res. 1996;79:898-908), on page 903, the paragraph headed “Wave Velocity” should read “We calculated a propagation velocity (v) of the intercellular Ca2+ wave of 5±2 μm/s (n=9) from the wave-velocity equation v=2πfd/Δθ, using values for intercellular phase delay (Δθ) of the dominant wave component at frequency f and internuclear distance d, between adjoining cells.” (Emphasis added.) Also, the first sentence of the legend for Figure 5 should read as follows: “Endothelial [Ca2+]i profiles for a single lung capillary are shown during periods of capillary perfusion with blood or with Ca2+-free dextran-Ringer (dextran in Ca2+-free buffer containing 0.5 mmol/L EGTA).” (Emphasis added.) The concentration was stated correctly in the text.In the article by Bernstein et al, “Function and production of nitric oxide in the coronary circulation of the conscious dog during exercise” (Circ Res. 1996;79:840-848), on page 846, two x-axis labels for Figures 3 and 4 were omitted by printer error. The figures are correctly reproduced below.Download figureDownload PowerPoint Figure 3. The relationship between myocardial oxygen consumption (MVO2) and myocardial work. MVO2 was calculated as the arterial-CS oxygen difference multiplied by mean CBF, and myocardial work (A) was estimated by the triple product (LV systolic pressure times LV dP/dt times heart rate, in millions). Both MVO2 and the triple product increased with exercise in a linear fashion (y=0.11x+5.1; R2=.96) in the normal state. After blockade of NO synthesis with NLA, there was a significant elevation in the slope (n=15, P<.05) of this relationship (y=0.15x+5.3; R2=.98). When MVO2 is compared with cardiac minute work (pressure-volume loop area multiplied by heart rate) (B), a similar effect is revealed. Blockade of NO synthesis increases the slope of the work–oxygen consumption relationship (n=5, P<.05). The triple product was compared with cardiac minute work (C), and the two are linearly related.Download figureDownload PowerPoint Figure 4. CS NOX levels before (triangles) and after (circles) blockade of NO synthesis with NLA (A). NOX release was calculated as the difference between the arterial and CS plasma NOX (B). There was a significant release of NOX during exercise. After NLA, there was a significant reduction in NOX release, reaching a value that was not different from zero. NOX production (NOX release multiplied by mean CBF) increased significantly with exercise and was abolished with NLA (C). *P<.05 vs zero; **P<.05 vs rest; and #P<.05 vs pre-NLA (normal). Previous Back to top Next FiguresReferencesRelatedDetails December 1, 1996Vol 79, Issue 6 Advertisement Article InformationMetrics https://doi.org/10.1161/01.RES.79.6.1218 Originally publishedDecember 1, 1996 Advertisement

Microstructure characteristics of a rapidly solidified Al-Si-Ti-Pb alloy

The microstructure and annealing behavior of a rapidly solidified Al-5.10Si-1.00Ti-0.70Pb (wt.%) alloy have been examined. As the cooling rates were increased from 10 to 106K/s, the dendritic structures of α-Al were replaced in order by cellular and microcellular structures; the interdendritic or intercellular phases changed from prolonged sheets into discrete rounded particles and from several phases enriched in Si, Ti, Pb, Fe, or P into a single second Pb phase. At the cooling rate of 106K/s, approximately 5.0 wt.% Si and 1.0 wt.% Ti were trapped in the α-Al microcells, whereas only the dispersed Pb particles were observed at the cell boundaries and had an epitaxial cube-cube orientation relation with α-Al matrix. The as-solidified microstructure obtained at the cooling rate of 106K/s has been found to be stable up to 450 °C for 5 h. After annealing at 450 °C for 100 h, a high volume fraction of finely dispersed phases was observed. These dispersed phases are thought to be very important in raising the room- and elevated-temperature performance and wear-resistance capability of the alloy. The precipitation characteristics are thought to result mainly from the effect of the element Ti.

The structure of a rapidly solidified Al-Fe-Ti-C alloy

The microstructures of melt-spun Al-2.03 Fe-0.46 Ti-0.35 C (at %) superheated to 1523 K (ribbon I), and 1673 K (ribbon II), respectively, before quenching, have been characterized using analytical electron microscopy and X-ray diffraction. A duplex microstructure has been observed for ribbon I, consisting of a microcellular region, across a sharp transition, followed by a coarser cellular or dendritic structure. The intercellular phases consisted mostly of Al6Fe (few of Al3Fe) and the dispersed TiC particles distributed in the α-Al matrix with an exact orientation relationship. However, the microstructure of ribbon II comprised uniform, fine-scale dispersions of Al6Fe phase in α-Al grains, and larger size, elongated amorphous phase particles located along the grain boundaries, and approximately 0.46 at % Ti and 0.35 at % C dissolved in the α-Al matrix. During the annealing of ribbon II, the amorphous phase transformed to αT-AlFeSi phase, the Al6Fe dispersoids grew upwards and Al3Fe, TiC particles precipitated in the α-Al matrix. TiC phase formed both in ribbon I and in annealed ribbon II all had an atomic composition of TiC0.79 (the nominal atomic percent ratio for the alloy $$X_C /X_{T_{_j } } $$ was 0.74) and a lattice parameter of 0.424 nm. Moreover, there is a cube-cube orientation relationship between TiC and α-Al matrix with a disregistry δ=0.049. In addition, the solidification characteristics of rapid solidification processing (RSP) Al-Fe-Ti-C alloy and mechanism of TiC formation have been discussed.

The microstructure of CO 2 laser welds in an Al-Fe-V-Si alloy

Autogenous, bead-on-plate CO 2 laser welding of an Al-8.5wt.%Fe-1.2wt.%V-1.7wt.%Si alloy was performed on 2 mm thick sheet. The microstructural characteristics of the fusion zone were investigated using optical, scanning and transmission electron microscopies, and the fusion zone microstructure was compared with that of the base metal. In the as-welded condition the fusion zone microstructure consisted of faceted precipitates around 10 μm in size, embedded in a cellular-dendritic α-Al matrix with a submicrometre intercellular phase. This fusion zone structure was significantly different from that of the powder-metallurgy base alloy which contained Al 12(Fe, V) 3 dispersoids in a fine grained α-Al matrix. Detailed electron microscopy showed that the faceted precipitates in the fusion zone have the Al m Fe-type crystal structure ( m ≈ 4) and are enriched in Si, Fe and V compared with the α-Al. A crystalline Fe- and Si-rich phase formed at the cell boundaries. Over the range of conditions examined, changing the welding speed did not alter significantly the microstructural development in the fusion zone. As expected, the presence of coarse intermediate phase particles meant that the fusion zone had a significantly lower room temperature Vickers hardness than the base metal.

Microstructures and mechanical properties of extruded bars made from rapidly solidified steel powder (RSP): D.H. Yeo et al, (Seoul National Univ, Korea), J. Korean Inst. of Metals, Vol 28, No 11, 1990, 990–995, (In Korean)

Autogenous, bead-on-plate CO2 laser welding of an Al-8.5wt.%Fe-1.2wt.%V-1.7wt.%Si alloy was performed on 2 mm thick sheet. The microstructural characteristics of the fusion zone were investigated using optical, scanning and transmission electron microscopies, and the fusion zone microstructure was compared with that of the base metal. In the as-welded condition the fusion zone microstructure consisted of faceted precipitates around 10 μm in size, embedded in a cellular-dendritic α-Al matrix with a submicrometre intercellular phase. This fusion zone structure was significantly different from that of the powder-metallurgy base alloy which contained Al12(Fe, V)3 dispersoids in a fine grained α-Al matrix. Detailed electron microscopy showed that the faceted precipitates in the fusion zone have the Alm Fe-type crystal structure (m ≈ 4) and are enriched in Si, Fe and V compared with the α-Al. A crystalline Fe- and Si-rich phase formed at the cell boundaries. Over the range of conditions examined, changing the welding speed did not alter significantly the microstructural development in the fusion zone. As expected, the presence of coarse intermediate phase particles meant that the fusion zone had a significantly lower room temperature Vickers hardness than the base metal.