Abstract: A versatile beach towel (10) comprising a circular piece of absorbent fabric (12). A binding (14) is attached to a circumferential edge (16) of the circular piece of absorbent fabric (12). The binding (14) has a hollow passageway (18) therethrough. A drawstring (20) extends through the hollow passageway (18) in the binding (14). When the drawstring (20) is pulled tight, the binding (14) will close up and the circular piece of absorbent fabric (12) will turn into a pouch (22) for holding objects therein.

Abstract: A circuit board material is disclosed which includes a support layer, at least one electrical resistance layer having a preselected resistivity adhered to the support layer, a barrier layer adhered to the electrical resistance layer, and a conductive layer adhered to the barrier layer. The barrier layer is capable of protecting the resistance layer from attack by alkaline ammoniacal copper etchants. A method of producing the circuit board material is also disclosed.

Abstract: A laminated steel sheet for dry forming drawn and ironed cans wherein the steel sheet comprises a steel containing iron, carbon, manganese, aluminum, silicon, phosphorus, sulfur and optionally titanium and/or niobium and wherein the steel sheet is electrolytically chromium-coated and covered on both sides with a 10-50 .mu.m thick thermoplastic resin layer. The sheet sheet has a crystal grain size of 8-30 .mu.m, a surface roughness of 0.05-0.6 .mu.m and a thickness of 0.15-0.3 mm.

Abstract: A substrate includes a flat principal member having a surface, and at least three first holding portions projecting from the principal member. Each of the first holding portions includes a pair of horizontal contact surfaces which are parallel to the surface of the principal member and which are disposed facing opposite to each other. At least three second holding portions are also disposed on the principal member, each of the second holding portions including a pair of vertical contact surfaces which are perpendicular to the surface of the principal member and are disposed facing opposite to each other. Method and apparatus for holding such a substrate includes structure and steps for grasping the at least three first holding portions and the at least three second holding portions. The structure and functions provide a platform for stably gripping a substrate.

Abstract: An improved magnetic-recording disk and a process for manufacturing magnetic-recording disks are disclosed. An electrically conductive hard coating is deposited upon a ceramic substrate. This coating can be one from the group including the nitrides, carbides, and borides of titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, or tungsten. Graded interfacial diffusion or pseudo-diffusion layers are formed between the ceramic substrate and the coating by the elemental metal present in the coating. Magnetic-recording media is then deposited upon the electrically conductive coating. Optionally, a texturable coating that is softer than the hard coating can be placed over the electrically conductive hard coating before the magnetic-recording media is deposited. This texturable coating limits the depth to which abrasive tape texturing can take place.

Abstract: Loom components such as reed dents or weft brake lamellae that, during operation, are exposed to frictional abrasion by a moving weft thread, are made of cold rolled strip steel or of refined nitrided steels. The components are then exposed to a heat treatment at a temperature larger than 480.degree. C. for a duration of more than two hours, preferably up to 8 hours. A thermo-chemical treatment is performed simultaneously with the heat treatment to harden at least those surface areas of the components that in operation will be exposed to the frictional abrasion.

Abstract: Methods for cracking hydrocarbons in reactor systems having improved resistances to carburization and coking. The reactor system comprises a steel portion having provided thereon a Group VIB metal protective layer to isolate the steel portion from hydrocarbons, applied to a thickness effective for isolating the steel portion from the hydrocarbon environment. The protective layer is anchored to the steel substrate through an intermediate carbide-rich, bonding layer.

Abstract: An article is coated with a multilayer coating comprising a nickel layer deposited on the surface of the article, a nickel-tungsten-boron alloy layer deposited on the nickel layer, a chrome layer deposited on the nickel-tungsten-boron alloy layer, a refractory metal, preferably zirconium, strike layer deposited on the chrome layer, and a refractory metal compound, preferably zirconium nitride, deposited on the refractory metal strike layer. The coating provides the color of polished brass to the article and also provides abrasion and corrosion protection.

Abstract: The improved sputtered memory disk of the present invention comprises a substrate coated with a nucleating layer, a subsequent magnetic layer, and a protective coating. As a result of texturing in the circumferential direction and epitaxy involving the nucleating layer, an anisotropic orientation of coercivity in the circumferential direction has occurred during the sputtering that provides an improved memory disk having enhanced coercivity, a reduced amplitude modulation, an improved squareness of the hysteresis loop, e.g., lower switching field distribution, and a high production, relatively low cost production system. As a result, a higher recording density due to the higher coercivity and low switching field distribution can be experienced with the magnetic disk of the present invention.

Abstract: Sheet glass (2) is rendered fire resistant such that it will not shatter under a build-up of heat to 900.degree. C., by providing a thin coating (1) on one or both its surfaces, the coating being stable and adherent to the glass at up to 900.degree. C., the coating preferably comprising an oxide, nitride, oxynitride or fluoride of a metal or of silicon, or a metal silicide, the sheet having been toughened by tempering before or after coating and having its edges (3) ground and polished before the tempering step to remove all imperfections therefrom.

Abstract: A ceramic substrate has a five-layered thin metallic film thereon. The first layer is Ti, Zr, Cr and/or W; the second layer is Ni and/or Mo; the third layer is one or more metals of group Ib in the periodic table; the fourth layer contains the same metals as the second layer and the fifth layer contains the same metals as the third layer.

Abstract: A soft-magnetic multilayer thin film produced by electroplating, wherein an anode-dissolution process is effected by intermittently applying a reverse d.c. bias current with respect to the plating-forward current. Involving the anode-dissolution process allows the formation of a re-dissolution effect layer differing in crystal structure from the plated film layer. A soft-magnetic multilayer thin film characterized by having a multilayer film structure which comprises a plated layer and a re-dissolution effect layer laminated to each other and which the plated layer is at least magnetically isolated. Further, a method of manufacturing a soft-magnetic multilayer thin film having a multilayer film structure magnetically isolated only through plating, which is offered by introducing the anode-dissolution process.

Abstract: The hard carbon coating-clad base material of the present invention comprises a base material, a substratal metal coating formed on the base material by a wet plating process, an intermediate metal coating comprising a titanium or chromium coating formed on the substratal metal coating by a dry plating process and a silicon coating formed on the titanium or chromium coating by a dry plating process, and a hard carbon coating formed on the silicon coating by a dry plating process. According to the present invention, a highly reliable hard carbon coating which is excellent in corrosion resistance, adhesion and abrasion resistance can be formed even on brass or an iron base material having poor corrosion resistance, such as SK steel and martensitic and ferritic stainless steels.

Abstract: A magnetic disc according to this invention is of a structure in which underlying layer and magnetic layer are formed in succession on non-magnetic substrate, and one non-magnetic intermediate layer or more and one second magnetic layer or more are further stacked one after another thereon. The non-magnetic intermediate layer is formed as film layer by sputtering, and film thickness calculated by film formation rate and film formation time is 0.2 nm.about.1.0 nm. Thus, with this magnetic disc, coercive force is improved. Accordingly, signals can be recorded at higher density. As a result, application to magnetic disc devices of larger memory capacity can be made.

Abstract: A magnetic recording medium comprising a non-metallic substrate having a seedlayer thereon of carbon or silicon. The seedlayer improves the magnetic recording characteristics of a subsequent magnetic layer by smoothing out irregularities on the non-metallic substrate surface such that a surface of the seedlayer adjacent the magnetic layer is smoother than the surface of the substrate.

Abstract: In a magnetoresistive read transducer, a material which is inert with respect to the soft film magnetic biasing layer is formed at the surface of the substrate prior to soft film deposition. In a preferred embodiment of the present invention, a substrate surface layer of metal such as Cr or Ta is used. These metals have high resistivity due to partial oxidation when deposited on the substrate to reduce shunting of sensing current through the magnetoresistive layer, and further acts as a barrier to protect the soft film from substrate interface contamination. The surface layer also acts as a seed layer to set the soft film magnetization orientation in a well-defined direction therefore reducing magnetic instability.

Abstract: Proposed is a magnetic recording medium consisting of a non-magnetic substrate and a magnetic recording layer formed thereon by the method of sputtering, in which the non-magnetic substrate is a disk of single crystal silicon having a surface of the crystallographic orientation of (100), the surface roughness Rp being 40 nm or smaller. By virtue of the use of the unique material for the substrate, the magnetic recording layer is outstandingly stable as compared with conventional aluminum or glass substrates and the magnetic layer formed thereon by sputtering has a greatly improved coercive force of 1300 oersted or higher.

Abstract: A thin-film multilayered recording medium is disclosed. The medium contains two or more magnetic thin-film sublayers separated by an isolation layer having an axial composition gradient.

Abstract: Laminates of magnetic and magnetic quenching laminae are provided for use as magnetic thin film laminates for use in magnetic recording heads. The use of these films significantly reduces the number of domains and Barkhausen noise levels in such recording heads.

Abstract: A surface of a non-magnetic base plate is first coarsened to a required surface roughness and an ultrasonic vibration is then applied to the surface of the non-magnetic base plate while the nonmagnetic base plate is immersed in a liquid. Thereafter, a magnetic recording layer and a protective layer are successively formed on the surface of the non-magnetic base plate thereby to produce a magnetic recording medium. It is preferable that the frequency of a ultrasonic is within a range from 200 kHz to 1600 kHz. Surface fractional properties of the magnetic recording medium can adequately be controlled without variation of floatation height of a magnetic head during its running by varying an ultrasonic oscillation output and an ultrasonic processing time.

Abstract: A roll used for tensioning a canvas belt used to hold paper against a dryer. The roll includes a main cylindrical body formed of steel. A layer formed of a metal harder than steel is disposed over the outer surface of the main body. The metal layer is formed with a channel around its center so as to define two spaced roll end sections of a common diameter. A fluororesin layer is disposed in the metal layer channel and is shaped so as to have an outer surface of a diameter equal to that of the metal layer end sections.

Abstract: It is an object of the present invention to provide a magnetoresistance effect element which has a film with a spin valve structure or an artificial lattice film having good soft magnetic characteristics, and which can be applied to a high-sensitivity magnetic head. The present invention provides a magnetoresistance effect element including a stacked film formed on a substrate by sequentially stacking a ferromagnetic film containing as its main constituents at least one elements selected from the group consisting of Co, Fe, and Ni, a nonmagnetic film, and the ferromagnetic film, wherein the two ferromagnetic films are not coupled with each other, and the closest packed plane of each ferromagnetic film is oriented in a direction perpendicular to the film surface.

Abstract: A magnetic recording medium is constructed with a substrate made of glass, one or two underlayers, and a magnetic film. In order that the easy magnetization axis of the magnetic film is parallel to the magnetic film, an underlayer having an NaCl crystallographic structure is superposed on the substrate. A magnetic film made of a Co based alloy having a hexagonal close packed crystallographic structure is formed on this underlayer, putting an underlayer made of a material having a body centered cubic crystallographic structure therebetween at need. Magnetic anisotropy of the magnetic film is increased by forming grooves in a predetermined direction in a surface portion of the substrate. These grooves play a role also for defining the orientation of the underlayer made of the material having an NaCl crystallographic structure.

Abstract: Disclosed is an artificial multilayer in which ferromagnetic layers and nonmagnetic layers are alternatively laminated, wherein a uniaxial magnetic anisotropy is introduced into the ferromagnetic layers in a predetermined direction, thereby controlling the gradient of the relative change of resistivity to the change of external magnetic field. The uniaxial magnetic anisotropy is introduced into the ferromagnetic layers by applying a magnetic field along the surface of ferromagnetic layers during the formation thereof.

Abstract: A carbonaceous, refractory or metal alloy substrate material coated with a refractory material, the refractory material including at least one of borides, silicides, nitrides, aluminides, carbides, phosphides, oxides, metal alloys, inter-metallic compounds and mixtures of one of titanium, chromium, zirconium, hafnium, vanadium, silicon, niobium, tantalum, nickel, molybdenum and iron and at least one refractory oxide of rare earth metals. An aluminum production cell including a component made up of a material coated with the coating described above is also disclosed.

Abstract: A high-density longitudinal recording medium comprising a CoPtCrB alloy with a chromium content in excess of 17 atomic percent exhibits high coercivity, low noise, and high Curie temperatures. Films are prepared by sputter depositing a chromium or chromium alloy underlayer on a non-magnetic substrate. A strong [100] crystallographic orientation of the underlayer is required to achieve a low noise, high coercivity medium. This orientation is achieved by depositing the underlayer on a negatively biased substrate under high temperature, low pressure conditions. The oriented underlayer prevents the subsequently deposited CoPtCrB alloy from orienting itself in its preferred, c axis vertical orientation. The CoPtCrB alloy comprises 4 to 12 percent platinum, 18 to 23 percent chromium and 2 to 10 percent boron.

Abstract: A magnetoresistance effect element having a substrate, a buffer layer of a metal selected from the group consisting of chromium, tungsten, titanium, vanadium, manganese and their alloys which is formed on the substrate, and at least two magnetic thin layers which are laminated with interposing a non-magnetic thin layer therebetween on the metal thin layer, wherein adjacent magnetic thin layers through the non-magnetic thin layer have different coercive forces. This magnetoresistance effect element has an increased magnetoresistance ratio.

Abstract: A substrate plate of plastic material instead of glass for the manufacture of a metal mold for the production of optical registration carriers of plastic material. Polyether imide is a suitable plastic material for forming the substrate plate. A suitable molding process is injection molding, wherein a highly polished mold is used.

Abstract: A metallic component of a gas-turbine installation is formed of a nickel-based base material and at least two coating layers superimposed on the base material for improving corrosion-resistance thereof. The coating layers include a first layer having a composition and/or thickness for resisting corrosive attack of the nickel-based base material at temperatures of 600.degree. C. to 800.degree. C. (HTCII), and a second coating layer having a composition and/or thickness for resisting corrosive attack of the base material at temperatures of 800.degree. C. to 900.degree. C. (HTCI).

Abstract: The corrosion resistance inherent in stainless steel is further improved by a cladding layer provided on the surface thereof. The cladding layer is formed of a coating material which is applied onto the surface of the stainless steel and, then, burnt to be fused by laser beams. The coating material contains a larger amount of Cr than that of the stainless steel. The thus fused material and a fused portion of the stainless steel are mixed with each other to form the cladding layer of remarkable corrosion resistance due to a larger amount of Cr contained therein. The formation of the cladding layer on the inner surface of a small diameter pipe is enabled by a coating film shaping device which has a jig for shaping the applied material into a film of a uniform thickness and by a laser irradiation torch which has an arrangement for emitting the laser means radially outward from the inside of the pipe.

Abstract: A magnetic recording medium capable of making a high-density recording, with improved magnetic characteristics such as coercive force (Hc) and other factors, in which the flatness of the surface of a magnetic recording medium is maintained, and a method for the manufacture thereof are disclosed; by disposing a non-magnetic metal buffer layer 6 between a non-magnetic glass substrate 1 and a non-magnetic metal under layer 2 and keeping a ratio d.sub.1 /d.sub.2 of the half bandwidth of an X-ray diffraction peak of the metal buffer layer 6 and the metal under layer 2 predetermined values, a large increase in coercive force (Hc) can be obtained; in addition, by controlling the film thickness .delta. of the metal buffer layer 6 and the base substance temperature (T) when the metal buffer layer 6 is formed, magnetic characteristics such as squareness (S), coercive force squareness (S*), coercive force difference (.sub..DELTA. HC) and coercive force squareness difference (.sub..DELTA. S*) can be improved.

Abstract: A thin-film rigid disk magnetic medium is prepared having a non-magnetic substrate and a magnetic alloy layer formed on the substrate with a non-magnetic underlayer containing chromium as the main component interposed therebetween, where the magnetic alloy layer contains cobalt as the main component and not more than 8 atomic % of boron, not more than 40 atomic % of nickel, not more than 26 atomic % of chromium and not more than 10 atomic % of tantalum. Preferably, the magnetic alloy layer is formed by sputtering while a voltage relatively lower than the plasma potential is applied to the non-magnetic substrate.

Abstract: A magnetic recording medium comprising a non-magnetic substrate and a magnetic alloy layer formed on the substrate with a non-magnetic primer layer containing chromium as the main component interposed therebetween, wherein the magnetic alloy layer contains cobalt and nickel as the main components and not more than 8 atomic % of boron and has been formed by sputtering under such a condition that a negative bias voltage is applied to the non-magnetic substrate.

Abstract: A corrosion-resistant metal strip and method for making the same which is essentially lead free and is not highly reflective. The coating on the metal strip is a metallic coating comprised of tin and a very low weight percentage of lead. The coating alloy may also include antimony, bismuth, copper, zinc to improve the coating process and/or improve the properties of the tin coating. A metal layer may also applied to the surface of the metal strip prior to applying the metallic alloy coating.

Abstract: Thin film media characterized by the utilization of a substantially peritectic seed alloy layer which is sputter deposited so as to provide dispersed, substantially peritectic and homogenous globules underlying subsequently deposited media layers. These media layers may include a metal layer such as chrome and a magnetic layer such as an alloy of cobalt, chromium, and platinum and possibly other ingredients.

Abstract: The present invention provides a metal thin film magnetic recording medium in which an underlying Cr layer, a magnetic recording layer and a protection layer are laminated in this order on a non-magnetic medium substrate. The medium substrate comprises an NiPX layer laminated in this order on a non-metallic base plate such as a glass base plate or a carbon base plate. X is one or mope elements belonging to a group of 4, 5 and 6 in a periodic table, and the content X is less than 20 at % in total. A heat accumulating non-magnetic layer having excellent heat conductivity may be formed on the non-metallic base plate and laminated between the NiPX layer thereon.

Abstract: The invention relates to a process for manufacturing a toothed wheel, especially for a windshield wiper control device, of the kind having on one face a conductive strip. The process consists of providing in the wheel face an impression having a shape complementing the shape of the conductive strip, disposing the conductive strip in said impression, and securing the conductive strip with the front face of the toothed wheel. The front face has a border running along a peripheral edge of the impression and protruding at the border of said impression.

Abstract: A cobalt-platinum (CoPt) magnetic film is deposited onto a chromium (Cr) or tungsten (W) underlayer on a substrate, or is deposited directly onto the substrate and has an appreciable component of its C-axis which is parallel go the [00.2] direction, lying in the plane of the film whereby the resultant magnetic films exhibit coercivities from 2100-3000 oersteds.

Abstract: A method of manufacturing a stamper includes the steps of coating a flat surface of a substrate with photosensitive material; directing light to a specified position on the photosensitive material to expose it; developing the photosensitive material to make a minute photoresist pattern; etching the substrate to a specified depth with a mask of the photoresist pattern; removing the photoresist as the mask to make a glass master; arbitrarily forming a first nickel layer on a surface of the glass master; forming an intermediate layer of a metal having a smaller linear expansion coefficient than nickel over the first nickel layer; forming a second nickel layer on the intermediate layer to form a conductive film having a two- or three-stratum structure; arbitrarily subjecting the whole substrate to a process to make nickel passive; forming an electroformed layer on the conductive film by an electroforming process; and separating the conductive film from the glass master.

Abstract: A magnetic thin-film medium formed on a non-metallic substrate and having reduced noise characteristics, by virtue of a 5-50 .ANG., sputtered Cr-containing sublayer interposed between the substrate and a chromium underlayer. Also disclosed is a method of preparing the low-noise medium.

Abstract: This invention relates generally to foil laminated tabletops and to methods for their manufacture. Tabletops according to the present invention can be laminated over their entire upper and side surfaces with a continuous sheet of thin foil, the foil typically comprising a plastic material. The foil layer ends at an angular lower edge where the side surface intersects the lower surface of the tabletop. By providing an angle preferably greater than about 120.degree. about the lower edge, the lower edge of the tabletop preferably does not feel sharp and the edge of the foil is at least partially hidden from view. The present invention also provides foil laminated tabletops having an upper surface provided with functional retaining recesses for retaining items on the tabletop.

Abstract: A method and system are disclosed for locally introducing fluid, such as a gas, at a predetermined location into molten resin downstream from a resin injection aperture to form a hollow part. The gas is utilized at the localized area to distribute the molten resin, to eliminated molded in stress and to prevent formation of sink marks in the part during resin solidification. An overflow reservoir outside of the mold cavity is filled with the resin during resin injection and then the gas is introduced into the reservoir through a fluid aperture and into the part. The reservoir creates a cocoon of solidified material to act as a seal to prevent gas leakage. One hollow body formed by the method and system includes a substantially endless hollow body portion with a fluid opening for communicating the interior of the hollow body portion with the locally introduced fluid. The hollow body provides an internal gas manifold and means for greater structural integrity.

Abstract: A magnetic recording disk has a layered structure comprising a metal substrate, a layer of NiP atop the metal substrate, the NiP layer having a surface roughness of less than 2.0 nanometers RMS, a metal layer over the polished NiP layer, the metal layer having a desired textured outer surface as a result of the sputter deposition, the textured outer surface being characterized by a cobblestone-like metallic grain structure with between 10 and 100 grains per square micron, an RMS surface roughness of between 1.0 and 8.0 nanometers, and with peak heights as measured from the mean plane of the surface over a 10 micron square area of between 2.0 and 20.0 nanometers, a magnetic layer atop the metal layer.

Abstract: A semiconductor wafer includes a notch or a hole used in preparing an orientation flat on the wafer. The notch in the wafer includes a side that is perpendicular to the surfaces of the wafer and aligned along a cleavage plane of the wafer for forming the orientation flat by cleaving. A hole in a wafer preferably includes an axis aligned along the cleaving plane. A sharp, non-rounded cleavage is formed by preparing the notch or hole after the completion of any etching processes or other steps that may round the edges of the flat. The sharp edges aid in achieving a precision alignment using the orientation flat.

Abstract: A surface anti-scuff device and system is disclosed wherein an anti-scuff member in the form of a strip of material having a high degree of abrasion resistance and a high degree of scuff resistance such as CORDURA.RTM. PLUS is mounted on each tire of a vehicle whereby the tires can move over the surface without scuffing the surface.

Abstract: A magnetic recording medium comprising:a precoat layer, having a thickness of 30 to 14000 .ANG., consisting of any of V (vanadium), Mo (molybdenum), NiP (nickel-phosphorus), C (carbon), Zr (zirconium) or Al (aluminum) formed on a non-magnetic, mirror-surface substrate 1, anda Cr (chromium) layer as a primer layer 3 and a Co (cobalt) alloy layer as a magnetic layer 4 laminated in order on the precoat layer 2.

Abstract: Foil for covering an impression cylinder of a rotary offset printing press for first-form and perfector printing is formed of a chemically and wear-resistant rigid support layer having good ink transfer behavior and having a structured surface with statistically uniformly distributed convex and concave structural elements thereon, and a microroughness-reducing chromium layer disposed on the rigid support layer and forming a sheet-guiding outer cylindrical surface of the impression cylinder, respective peaks being formed on the convex structural elements for supporting a sheet thereon, each of the convex structural elements having an oval shape with a radius of curvature increasing from the respective peak thereof to a transition into respective concave structural elements adjacent thereto.

Abstract: The corrosion resistance inherent in stainless steel is further improved by a cladding layer provided on the surface thereof. The cladding layer is formed of a coating material which is applied onto the surface of the stainless steel and, then, burnt to be fused by laser beams. The coating material contains a larger amount of Cr than that of the stainless steel. The thus fused material and a fused portion of the stainless steel are mixed with each other to form the cladding layer of remarkable corrosion resistance due to a larger amount of Cr contained therein. The formation of the cladding layer on the inner surface of a small diameter pipe is enabled by a coating film shaping device which has a jig for shaping the applied material into a film of a uniform thickness and by a laser irradiation torch which has an arrangement for emitting the laser means radially outward from the inside of the pipe.

Abstract: A method for producing a tin free steel having double layers consisting of a lower layer of flatly deposited metallic chromium and an upper layer of insoluble hydrated chromium oxide which is characterized by a dissolution of soluble hydrated chromium oxide after the formation of three layers consisting of a bottom layer of metallic chromium, a middle layer of insoluble hydrated chromium oxide and an upper layer of soluble hydrated chromium oxide on a steel base by using a chromic acid electrolyte with a small amount of fluoride compound. By using this tin free steel, a welded can body can be produced at high speed without the removal of the plated layer in the welded part because this tin free steel has an excellent weldability.

Abstract: A longitudinal magnetic recording medium comprising a non-magnetic substrate having a texture with a arithmetric average roughness Ra in a circumferential direction of at least 20 .ANG. and a magnetic alloy layer comprising cobalt and chromium as the main components, formed on the substrate, wherein the magnetic alloy layer has (i) a feature that when the orientation degree of the hcp crystal structure is represented by the diffraction ray intensity of electron diffraction by transmission electron diffractiometry, the intensity ratio of the electron diffraction ring in the Co (002) plane between the circumferential direction and the radial direction of the substrate is at least 3, and (ii) a segregation structure having low chromium concentration regions surrounded by high chromium concentration regions, the diameters of the defined low chromium concentration regions being within a range of from 80 to 500 .ANG.