The phase transformation dynamic and electrical conductivity equations of the aged Cu-2.7Ti-2.5Ni-0.8V alloy were established in this work. The microstructure evolution and precipitated phases were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The mechanical properties were tested using a hardness testing machine and universal test machine, and the electrical conductivity was measured by the eddy conductivity gauge. The results show that NiTi intermetallic compounds are formed during the solidification, and these phases such as Ni3Ti and NiV3 are precipitated after aging treatment. The fracture morphology displays that a large number of shallow and equiaxed dimples occur on the tensile fracture, indicating a typical ductile fracture. After aging treatment at 450°C for 240 min, the hardness, tensile strength, elongation and electrical conductivity of the Cu-2.7Ti-2.5Ni-0.8V alloy are 184 HV, 459 MPa, 6.3% and 28.72% IACS, respectively.

The technology of high-pressure die-casting (HPDC) of aluminum alloys is one of the most used and most economical technology for mass production of castings. High-pressure die-casting technology is characterized by the production of complex, thin-walled and dimensionally accurate castings. An important role is placed on the effective reduction of costs in the production process, wherein the combination with the technology of high-pressure die-casting is the possibility of recycling using returnable material. The experimental part of the paper focuses on the analysis of a gradual increase of the returnable material amount in combination with a commercial purity alloy for the production of high-pressure die-castings. The returnable material consisted of the so-called foundry waste (defective castings, venting and gating systems, etc.). The first step of the experimental castings evaluation consisted of numerical simulations, performed to determine the points of the casting, where porosity occurs. In the next step, the evaluation of areal porosity and microstructural analysis was performed on experimental castings with different amounts of returnable material in the batch. The evaluation of the area porosity showed only a small effect of the increased amount of the returnable material in the batch, where the worst results were obtained by the casting of the alloy with 90% but also with 55% of the returnable material in the batch. The microstructure analysis showed that the increase in returnable material in the batch was visibly manifested only by a change in the morphology of the eutectic Si.

The study investigates the effect of heat treatment on the microstructure evolution and properties of an age-hardened ­Cu-3Ti-2Mg alloy. The precipitated Cu2Mg and β'-Cu4Ti phases consequently yield a depletion of the Cu matrix in regards to Ti and Mg solutes, which enhances the electrical conductivity. The Cu2Mg Laves phase and β'-Cu4Ti phase precipitates increase the hardness of the alloy due to the consistency and coherency of the later phase. However, the decrease of hardness is mainly associated with the coarse microstructures, that can be formed due to the phase transformation from metastable β'-Cu4Ti phase to more stable Cu3Ti phase. In the range of experiments, the optimum process is solution treatment at 700°C for 4 h, with subsequent age-hardening at 450°C for 4 h. The electrical conductivity, hardness, tensile strength, and elongation of the Cu-3Ti-2Mg alloy were 15.34 %IACS, 344 HV, 533 MPa, and 12%, respectively.

This study was undertaken to investigate the effect of severe plastic deformation (SPD) by extrusion combined with reversible torsion (KoBo) method on microstructure and mechanical properties of Al-5Cu and Al-25Cu alloys. The extrusion combined with reversible torsion was carried out using reduction coefficient of λ = 30 and λ = 98. In this work, the microstructure was characterized by light microscopy (LM), scanning electron microscopy (SEM) and scanning transmission electron microscopy (STEM). Compression test and tensile test were performed for deformed alloys. The binary Al-5Cu and Al-25Cu alloys consist of the face cantered cubic (FCC) α phase in the form of dendrites and tetragonal (C16) θ-Al2Cu intermetallic phase observed in interdentritic regions. The increase of Cu content leads to increase of interdentritic regions. The microstructure of the alloys is refined after applying KoB deformation with λ = 30 and λ = 98. Ultimate Tensile Strength (UTS) of Al-5Cu alloy after KoBo deformation with λ = 30 and λ = 98 reached about 200 MPa. UTS for samples of Al-25Cu with λ = 30 and λ = 98 increased compared to Al-5Cu alloy and exceed 320 MPa and 270 MPa respectively. All samples showed increase of plasticity with increase of reduction coefficient. Independently of reduction coefficient, the compressive strain of Al-5Cu alloys is about 60%. The Al-25Cu alloy with λ = 98 showed the value of compressive strain exceed 60%, although for this same alloy but with λ = 30, the compressive strain is only 35%.

A comprehensive understanding of melt quality is of paramount importance for the control and prediction of actual casting characteristics. Among many phenomenon that occur during the solidification of castings, there are four that control structure and consequently mechanical properties: chemical composition, liquid metal treatment, cooling rate and temperature gradient. The cooling rate and alloy composition are most important among them. This paper investigates the effect of the major alloying elements (silicon and copper) of AlSi-Cu alloys on the size of secondary dendrite arm spacing. It has been shown that both alloying elements have reasonable influence on the refinement of this solidification parameter

The ecological meanings clearly indicates the need of reducing of the concentration of the CO2in the atmosphere, which can be accomplished through the lowering of the fuel consumption. This fact implies the research for the new construction solutions regarding the reduction of the weight of vehicles. The reduced weight of the vehicle is also important in the case of application of the alternative propulsion, to extend the lifetime of the batteries with the reduction of recharge cycles. The use of cast alloy AlZnMgCu compliant of plastic forming class 7xxx alloy, are intended to significantly reduce the weight of the structures, while ensuring high strength properties. The wide range of the solidification temperature, which is more than 150°C, characterizes this alloy with a high tendency to create the micro and macro porosity. The study presents the relationship between the cooling rate and the area of occurrence and percentage of microporosity. Then the results were linked to the local tensile strength predicted in the simulation analysis. The evaluation of the microporosity was performed on the basis of the CT (computed tomography) and the analysis of the alloy microstructure. The microstructure analysis was carried out on test specimen obtained from the varying wall thickness of the experimental casting. The evaluation of the mechanical properties was prepared on the basis of the static tensile test and the modified low cycle fatigue test (MLCF).

Based on the example of the development process of the cast suspension of a special-purpose vehicle the application of the integrated engineering design methodology (ICME – Integrated Computational Materials Engineering) and the development of construction has been presented. Identification of the operating and critical loads, which are guidelines for carrying out the structure strength shaping process, material and technological conversion, are due to the needs and requirements of the suspension system and the purpose and objectives of the special mobile platform. The developed cast suspension element construction includes the use of high-strength AlZnMgCu aluminum alloy. The properties of the used alloy and designed shape allows for the transfer of assumed operating loads in normal exploitation conditions and in the dynamic, critical loads to the susceptibility to damage in the assumed casting areas. For the proposed design, conducted numerical analyzes includes the impact of the shock wave pulse on the occurrence of the destructive stress fields. Based on their distribution, the areas of possible decomposition of the structure of the design element were estimated. The results allowed to devise an element with predicted destructions that allow to absorb a significant part of the impact energy of the shock wave front, which is also the buffer zone for the propagation of destruction for the critical kinematic nodes of the system.

The present research was conducted on thin-walled castings with 5 mm wall thicknesses. This study addresses the effect of the influence of

different master alloys, namely: (1) Al-5%Ti-1%B, (2) Al-5%Ti and (3) Al-3%B, respectively on the structure and the degree of

undercooling (ΔTα = Tα-Tmin, where Tα - the equilibrium solidification temperature, Tmin - the minimum temperature at the beginning of

α(Al) solidification) of an Al-Cu alloy. The process of fading has been investigated at different times spent on the refinement treatment ie.

from 3, 20, 45 and 90 minutes respectively, from the dissolution of master alloys. A thermal analysis was performed (using a type-S

thermocouple) to determine cooling curves. The degree of undercooling and recalescence were determined from cooling and solidification

curves, whereas macrostructure characteristics were conducted based on a metallographic examination. The fading effect of the refinement

of the primary structure is accompanied by a significant change in the number (dimension) of primary grains, which is strongly correlated

to solidification parameters, determined by thermal analysis. In addition to that, the analysis of grain refinement stability has been shown

with relation to different grain refinements and initial titanium concentration in Al-Cu base alloy. Finally, it has been shown that the

refinement process of the primary structure is unstable and requires strict metallurgical control.

Ultra-precision testing is a very important procedure to secure the reliability of the products as well as for the technology development in the areas of semiconductor and display. Accordingly, companies manufacturing equipment for testing of semiconductor and display have been continuously executing researches for the improvement of the performances of test sockets used in test equipment.

Through this study, characteristics of the materials in accordance with the mechanical and electrical properties of Ni-30wt%Co alloy and newly developed Cu-2wt%Be alloy were analyzed in order to select the probe pin material of the socket, which is a key component used in the semiconductor testing equipment. In addition, finite element interpretation was executed by using Ansys Workbench 14.0 to comparatively analyze the finite element interpretation results and experimental results. Experiment was executed for the mechanical properties including tensile strength, elasticity modulus, specific heat, thermal expansion coefficient and Contact Force, for electrical properties, experiment on surface resistance, specific resistance and electrical conductivity was executed to measure the properties. It was confirmed that the results of finite element interpretation and experiment displayed similar trend and it is deemed that the Contact Force value was superior for Be-Co alloy.

Through this study, it was confirmed that the newly developed Be-Co alloy is more appropriate as probe pin material used as the core component of test socket used in the semiconductor testing equipment than the existing Ni-Co alloy.

The impact of small addition of zirconium in hypoeutectic commercial AlSi10MgCu alloys on their mechanical properties (hardness) in as cast and thermally treated conditions was investigated. Small addition of zirconium does not change significantly the as cast and heat-treated microstructure of investigated alloys except to reduce the SDAS and grain size of primary α-aluminium phases. Addition of zirconium up to 0.14 wt. percentage increases the hardness of investigated alloys in as cast conditions. The increase in the hardness of samples after various solid solution times can correlate very well with the formation of small needle like coherent Al3Zr particles.

High-pressure die casting results in a high quality surface and good mechanical properties of castings. Under the effect of pressure, integral and solid castings are achieved without a large number of foundry defects. The correct and proper setting of technological parameters plays a very important role in minimizing casting defects. The aim of the presented article is to determine the optimum maximum piston velocity for a casting in the high-pressure casting process with two height variants, depending on their internal quality. It is because the internal quality of particular castings is important in terms of proper functionality in operations where the biggest problem is the porosity of the casting. The main cause of porosity formation is the decreasing solubility of gases (most often hydrogen) during the melt solidification. Solubility represents the maximum amount of gas that can dissolve in a metal under equilibrium conditions of temperature and pressure. Macroporosity and microporosity were determined from the sections of the surfaces in the determined zones of the castings. Here, the results was that the macroporosity decreased with increasing piston velocity. Ideal microstructure was evaluated at a piston velocity of 3 m/s for both types of castings. On the other hand, the increase in tube size has shown that velocities of 3 m/s and higher, the tube is more prone to macroporosity formation. The highest hardness was achieved at the piston velocity of 2 m/s at both tube lengths.

An overview of the bibliography regarding the connection of knowledge about precious metal alloys and aspects of the use of computer aided technologies to the optimization of the jewelry casting processes is presented. An analysis of the usability of selected CAx systems was made: 1) for spatial design, called Rhinoceros 6 and 2) CAE system: NovaFlow & Solid (NF&S). The authors describe own research including data acquisition and evaluation of temperature variations during solidification of the selected Au-Ag-Cu alloy, with the identification of the phase transformations of this alloy. The intensity of heat exchange was changed (cooling of specimens under ambient temperature conditions – "normal" intensity and with the furnace – very slow cooling). The problem of completing the simulation database was pointed out and analyzed. Examples of simulations of casting selected jewelry (ring and signet) were given and compared with the result of the experiment realized in real conditions. It was confirmed that the optimization by combining experimental and simulation studies allows for the acquisition of new knowledge, and also facilitates the creation of new artistic designs of jewelry as well as performing the feasibility check, and then optimizing the chosen technology.

The paper presents the research data on structure, phase composition, defect substructure state, and microhardness of surface layers in the piston alloy Al-10wt%Si-2wt%Cu irradiated by an electron beam with various energy densities and pulse times. An important finding to emerge from the study is that the processing by an electron beam with an energy density of 10 J/cm2 brings about slight surface melting, whereas a weak thermal impact of an electron beam hardly changes the phase composition. Once an energy density of an electron beam is set 30 J/cm2, intermetallic compounds dissolve and numerous micropores arise. Irradiating by an electron beam with an energy density of 50 J/cm2, randomly located microcracks are detected on the treated surface with no regard to a pulse time. A structure of high-speed cellular crystallization with cells from 500 to 600 nm forms in the surface layer. A thickness of the modified layer is related to a beam energy density. As a beam energy density goes up, a thickness of a high-speed cellular crystallization layer increases. Atoms of Si, Cu, Ni, as well as a small quantity of Fe and Mg are detected in the surface, in thin layers surrounding crystallization cells. In a layer 60-80 μm below the irradiated surface, in material between high-speed crystallization cells, there are Si atoms and an insignificant number of Cu atoms. An analysis of a deeper material part has shown a structure similar to the as cast alloy. A drop of microhardness – if compared with the as cast material – is reported at an energy density of 10 J/cm2 because an energy amount supplied by an electron beam to the alloy surface is insufficient for melting of the material and dissolution of the intermetallic phase. A raise of a beam energy density up to 20-50 J/cm2 causes a max increase of microhardness up to 1.13 GPa for 40 J/cm2, 50 s, and up to 1.16 GPa for 40 J/cm2, 200 s.

To determine the relationships between operating conditions and tribological properties of Zn-30Al-3Cu alloy, its wear characteristics were investigated at wide ranges of oil flow rate, pressure and sliding velocity using a block-on-disk type test apparatus. The results are compared to those of SAE 660 leaded bearing bronze. Wear loss of these materials increased with sliding distance, pressure and sliding velocity, but decreased slightly with oil flow rate. The relationships between operating conditions and lubricated wear properties of Zn-30Al-3Cu alloy were determined by nonlinear regression analysis of the experimental data. Lubricated wear behavior of the zinc-based alloy was discussed in terms its microstructure and mechanical properties, and test conditions.

Comprehensive understanding of the melt quality is of vital importance for foundry man. The effect of each particular element need to be properly analysed. Therefore, the aim of this paper was to analyse the impact of various content of zirconium on the solidification path and structural characteristics (SDAS, grain size, porosity) of as cast commercial AlSi10MgCu alloys. It has been found that addition of zirconium up to 0.24 wt.% reduce significantly the grains size (from 3.5 mm to 1.2 mm), SDAS (from 57.3 µm to 50.4 µm) and porosity (from 19% to 5%), leading to production of sound cast parts.

Directed energy deposition (DED) is an additive manufacturing process wherein an energy source is focused on a substrate on which a feedstock material is simultaneously delivered, thereby forming a small melt pool. Melting, solidification, and subsequent cooling occur at high rates with considerable thermal gradients compared with traditional metallurgical processes. Hence, it is important to examine the effects of cooling rates on the microstructures and properties of the additive manufactured materials. In this study, after performing DED with various energy densities, we investigated the changes in the microstructures and Vickers hardness of cast Al-33 wt.% Cu alloy, which is widely used to estimate the cooling rate during processing by measuring the lamellar spacing of the microstructure after solidification. The effects of the energy density on the cooling rate and resultant mechanical properties are discussed, which suggests a simple way to estimate the cooling rate indirectly. This study corresponds to the basic stage of the current study, and will continue to apply DED in the future.

This study investigated the effect of adding Al–5Ti–1B grain refiner on the solidification microstructure and hot deformation behavior of direct-chill (DC) cast Al–Zn–Mg–Cu alloys. The grain refiner significantly decreased the grain size and modified the morphology. Fine-grained (FG) alloys with grain refiners exhibit coarse secondary phases with a reduced number density compared to coarse-grained (CG) alloys without grain refiners. Dynamic recrystallization (DRX) was enhanced at higher compression temperatures and lower strain rates in the CG and FG alloys. Both particle stimulated nucleation (PSN) and continuous dynamic recrystallization (CDRX) are enhanced in the FG alloys, resulting in decreased peak stress values (indicating DRX onset) at 450°C. The peak stress of the FG alloys was higher at 300-400°C than that of the CG alloys because of grain refinement hardening over softening by enhanced DRX.