R. Nowosielski

Structural, Magnetic and Crystallization Study of Fe-Based Bulk Metallic Glasses

The work presents the structural, thermal and magnetic properties analysis of Fe72B20Si4Nb4 bulk metallic glasses in as-cast state and crystallization study of bulk amorphous alloy after annealing process. The studies were performed on bulk metallic glasses in of rods form with diameter of 1,5 and 2 mm. The structure analysis of the samples in as-cast state and phase analysis of studied alloy after annealing process was carried out by the X-ray diffraction (XRD) methods. Mössbauer spectroscopy (MS) was also used to investigate the local structure for studied bulk metallic glasses. Thermal properties associated with glass transition, onset and peak crystallization temperatures was examined by differential scanning calorimetry (DSC). The soft magnetic properties examination of tested material contained initial magnetic permeability and disaccommodation of magnetic permeability.

Influence of Copper Addition on Glass Forming Ability, Thermal Stability, Structure and Magnetic Properties of Fe-Co-Based BMGs

The aim of the paper was investigation of the effect of Cu addition on glass forming ability (GFA), thermal stability, structure and magnetic properties of Fe-Co-based bulk metallic glasses (BMGs). The raw materials used in this experiment for the production of BMGs were pure Fe, Co, Cu and industrial Fe-B, Fe-Si, Fe-Nb ferroalloy. Investigations were carried out on BMGs in rods shaped with square section with side of 1.5mm. The structure of the investigated BMGs in rod form is amorphous. The addition of small amounts of Cu is effective in changing GFA and magnetic properties. The melting temperature - Tm remained almost constant for both investigated alloy. Two alloy compositions are at or very close to the eutectics, what according to ref. [1] should guarantee the best metallic glass-forming alloys. The investigated alloys have good soft magnetic properties. The successful synthesis of the Fe36.00Co36.00B19.00Si5Nb4 and Fe35.75Co35.75B18.90Si5Nb4Cu0.6 alloys with high GFA and good soft magnetic properties by using starting industrial alloys are encouraging for the future industry applications.

Structure of Fe-Based Metallic Glass after Crystallization Process

The work presents a crystallization process of Fe-based amorphous alloy by characterization of the influence of annealing temperature on structural changes and magnetic properties of Fe72B20Si4Nb4 metallic glass. The studies were performed on the samples in the form of ribbons and rods. Crystallization behaviour of the studied alloy was examined by X-ray diffraction (XRD) and transmission electron microscopy (TEM) methods. The studies of soft magnetic properties of tested material involved magnetic permeability, saturation induction, coercive field and magnetic after-effects measurements.

Crack initiation and fracture features of Fe–Co–B–Si–Nb bulk metallic glass during compression

The aim of the paper was investigation crack initiation and fracture features developed during compression of Fe-based bulk metallic glass (BMG). These Fe-based BMG has received great attention as a new class of structural material due to an excellent properties (e.g. high strength and high elasticity) and low costs. However, the poor ductility and brittle fracture exhibited in BMGs limit their structural application. At room temperature, BMGs fails catastrophically without appreciable plastic deformation under tension and only very limited plastic deformation is observed under compression or bending. Hence a well understanding of the crack initiation and fracture morphology of Fe-based BMGs after compression is of much importance for designing high performance BMGs. The raw materials used in this experiment for the production of BMGs were pure Fe, Co, Nb metals and nonmetallic elements: Si, B. The Fe–Co–B–Si–Nb alloy was cast as rods with three different diameters. The structure of the investigated BMGs rod is amorphous. The measurement of mechanical properties (Young modulus - E, compressive stress - ?c, elastic strain - ?, unitary elastic strain energy – Uu) were made in compression test. Compression test indicates the rods of Fe-based alloy to exhibit high mechanical strength. The development of crack initiation and fracture morphology after compression of Fe-based BMG were examined with scanning electron microscope (SEM). Fracture morphology of rods has been different on the cross section. Two characteristic features of the compressive fracture morphologies of BMGs were observed. One is the smooth region. Another typical feature of the compressive fracture morphology of BMGs is the vein pattern. The veins on the compressive fracture surface have an obvious direction as result of initial displace of sample along shear bands. This direction follows the direction of the displacement of a material. The formation of veins on the compressive fracture surface is closely related to the shear fracture mechanism. The results of these studies may improve the understanding on the fracture features and mechanisms of BMGs and may provide instructions on future design for ductile BMGs with high resistance for fracture.

Softmagnetic Nanocomposite with Silicon Polymer Matrix and Powdered Co68Fe4Mo1Si13,5B13,5

Structure, magnetic and mechanical properties of the nanocrystalline composite material of the SILAME® type were tested. The composite material was obtained by solidification of the nanocrystalline powder obtained in the high energy grinding of the initially crystallized Co68Fe4Mo1Si13,5B13,5 amorphous strip with the silicon polymer. The metallic powder was mixed with the silicon polymer in a different weight ratio and next the effect of Co68Fe4Mo1Si13,5B13,5 powder weight ratio on the magnetic and physical properties of the composite was investigated.

Structure, Mechanical Properties and Corrosion Resistance of MgCa5 and MgCa5Zn1 Alloys after Plastic Deformation

Binary Mg-Ca and ternary Mg-Ca-Zn alloys are a new group of magnesium materials, which can be used in many goods. Among others, biomedical applications of these alloys mainly involved surgical implants in the form of plates or screws. In order to improve mechanical properties and corrosion resistance of Mg-based alloys with Ca and Zn addition in as-cast state a plastic deformation was applied by using the KOBO extrusion method. The microstructure studies conducted by scanning microscopy show that the structure of the alloys after the plastic deformation exhibits banding character and the bands are oriented in the direction of an extrusion. A significant increase of mechanical properties was observed for MgCa5Zn1 alloy. After the plastic deformation, the corrosion potential determined for the MgCa5 and MgCa5Zn1 alloy is shifted into the positive direction, which may suggest the increase of corrosion resistance. Moreover, the MgCa5 alloy in as-cast state was completely dissolved after 288 h of immersion in Ringer’s solution. A volume of hydrogen evolution for the same alloy after plastic deformation showed a value of 35 ml/cm2.

Corrosion Study of Amorphous Mg67Zn29Ca4 Alloy

The aim of this paper was investigating the corrosion resistance of Mg67Zn29Ca4 metallic glass and evaluating the ability of use studied amorphous alloy for medical applications as biodegradable implants. For comparative purposes the corrosion studies of the amorphous Mg67Zn29Ca4 samples were performed in a few simulated body fluids at 37°C. The immersion tests were performed in Ringer’s solution, PWE (multielectrolyte physiological fluid) and 3%NaCl water solution. The amount of evolved hydrogen[ml/cm2] and a corrosion rate Vcorr [g/(day·m2)] of studied Mg67Zn29Ca4 alloy were compared. Surface morphology of metallic glass after corrosion study was performed using the scanning electron microscopy.In aim determination dissolution rate and amount of evolved hydrogen was simulated the environment of human body fluids during immersion tests. The work presents structure characterization and corrosion properties analysis of Mg67Zn29Ca4 bulk metallic glasses in the form of plates. Samples structure was analyzed by means of X-ray diffraction. Fractographic study a cross section of the sample in plates form was performed using scanning electron microscopy

Appraisal of the effectiveness of chosen management processes

The purpose of this article is to analyse an application of selected management methods and tools in an industrial environment at workstations. The article describes the general process of management at workstation. The methodology of quality problem solving and the following methodologies are described, such as: world class manufacturing, 5S method, 5Why, Kaizen and spaghetti chart applied on a workstation in order to solve present problems. Examples and analyses are based on results of selected methods and tools for an automotive company. Evaluation of application effectiveness of selected management methods and tools was performed. This appraisal defines which of the methods and tools used in a production plant is the most efficient and effective. Application of methods and tools should not only improve the quality of a machine and of a man, it has also an impact on the thinking and leading an employee towards pursuit of perfection.

Mechanical alloying of Fe-C alloys

In this article, the effect of chemical composition and time of high-energy milling on the average diameter of particles and grains of powder of Fe-C alloy is discussed. The mechanical alloying processes of the Fe-0,4% mass.C and Fe-6,67% mass.C alloys were conducted. The following investigations were carried out: XRD, SEM, TEM and laser distribution of size of particles method.