The paper deals with the impact of technological parameters on the heat transfer coefficient and microstructure in AlSi12 alloy using

squeeze casting technology. The casting with crystallization under pressure was used, specifically direct squeeze casting method. The goal

was to affect crystallization by pressure with a value 100 and 150 MPa. The pressure applied to the melt causes a significant increase of

the coefficient of heat transfer between the melt and the mold. There is an increase in heat flow by approximately 50% and the heat

transfer coefficient of up to 100-fold, depending on the casting conditions. The change in cooling rate influences the morphology of the

silicon particles and intermetallic phases. A change of excluded needles to a rod-shaped geometry with significantly shorter length occurs

when used gravity casting method. By using the pressure of 150 MPa during the crystallization process, in the structure can be observed an

irregular silica particles, but the size does not exceed 25 microns.

The paper presents the results of research on microstructure and impact strength of AlSi13Cu2 matrix composite reinforced by Ni-coating carbon fibers (CF) with a volume fraction of 5%, 10% and 15%. The composite suspensions were prepared using by stirring method and subsequently squeeze casted under different pressures of 25, 50, 75 and 100 MPa. As part of the study, fiber distribution in aluminum matrix was evaluated and variation in impact strength of composite as a function of the carbon fibers volume fraction and pressure applied were determined. It has been found that the presence of Ni coating on carbon fibers clearly improves their wettability by liquid aluminum alloy and in combination with the stirring parameters applied, composite material with relatively homogeneous structure can be produced. Charpy's test showed that the impact strength of composite reaches the highest value by carrying out the squeeze casting process at 75 MPa. In the next stage of research, it was found that the impact strength of composites increases with the increase of carbon fibers volume fraction and for 15% of fibers is close to 8 J/cm2. Observations of fracture surfaces have revealed that crack growth in the composites propagates with a quasi-cleavage mechanism. During the creation of the fracture, all fibers arranged perpendicular to its surface were sheared. At the same time, the metal matrix around the fibers deformed plastically creating characteristic ductile breaks. The fracture surface formation through the fibers indicates a cohesive and strong connection of the reinforcement with the matrix. In addition to the phenomena mentioned, debonding the fiber-matrix interfaces and the formation of voids between components were observed on the fracture surface.

The paper deals with squeeze casting technology. For this research a direct squeeze casting method has been chosen. As an experimental material, the AlSi12 and AlSi7Mg0.3 alloys were used. The influence of process parameters variation (pouring temperature, mold temperature) on mechanical properties and structure will be observed. For the AlSi7Mg0.3 alloy, a pressure of 30 MPa was used and for the AlSi12 alloy 50 MPa. The thicknesses of the individual walls were selected based on the use of preferred numbers and series of preferred numbers (STN ISO 17) with the sequence of 3.15 mm, 4 mm, 5 mm, 6.3 mm and 8 mm. The width of each wall was 22 mm and length 100 mm. The mechanical properties (Rm, A5) for individual casting parameters and their individual areas of different thicknesses were evaluated. For the AlSi7Mg0.3 alloy, the percentage increase of the tensile strength was up to 37% and the elongation by 400% (at the 8 mm thickness of the casting). For the AlSi12 alloy, the strength increased from 8 to 20% and the tensile strength increased from 5 to 85%. The minimum thickness of the wall to influence the casting properties by pressure was set to 5 mm (based on the used casting parameters). Due to the effect of the pressure during crystallization, a considerable refinement and uniformity of the casting structure occured, also a reduction in the size of the eutectic silicate-eliminated needles was observed.

The paper deals with the impact of technological parameters on the mechanical properties and microstructure in AlSi12 alloy

using squeeze casting technology. The casting with crystallization under pressure was used, specifically direct squeeze

casting method. The goal was to affect crystallization by pressure with a value 100 and 150 MPa. From the experiments we

can conclude that operating pressure of 100 MPa is sufficient to influence the structural characteristics of the alloy AlSi12.

The change in cooling rate influences the morphology of the silicon particles and intermetallic phases. A change of excluded

needles to a rod-shaped geometries with significantly shorter length occurs when used gravity casting method. At a pressure

of 100 MPa was increased of tensile strength on average of 20%. At a pressure of 150 MPa was increased of tensile strength

on average of 30%. During the experiment it was also observed, that increasing difference between the casting temperature

and the mold temperature leads to increase of mechanical properties.

The paper presents the results of research of impact strength of aluminum alloy EN AC-44200 based composite materials reinforced with

alumina particles. The research was carried out applying the materials produced by the pressure infiltration method of ceramic preforms

made of Al2O3 particles of 3-6m with the liquid EN AC-44200 Al alloy. The research was aimed at determining the composite resistance

to dynamic loads, taking into account the volume of reinforcing particles (from 10 to 40% by volume) at an ambient of 23°C and at

elevated temperatures to a maximum of 300°C. The results of this study were referred to the unreinforced matrix EN AC-44200 and to its

hardness and tensile strength. Based on microscopic studies, an analysis and description of crack mechanics of the tested materials were

performed. Structural analysis of a fracture surface, material structures under the crack surfaces of the matrix and cracking of the

reinforcing particles were performed.

NiTi alloys are successfully used in engineering and medical applications because of their properties, such as shape memory effect, superelasticity or mechanical strength. A composite with Mg matrix, due to its vibration damping properties, can be characterized by low weight and good vibration damping properties. In this study, a combination of two techniques was used for successful fabrication of Mg composite reinforced by NiTi alloy preform. The porous preforms synthesized by Self-propagating High-temperature Synthesis (SHS) from elemental powders were subsequently infiltrated with Mg by squeeze casting. The effects were examined with scanning electron microscope with EDS detector, X-ray diffraction and microindentation. The inspection has shown well-connected matrix and reinforcement; no reaction at the interface and open porosities fully infiltrated by liquid Mg. Moreover, analysis of samples’ fracture has exhibited that crack propagates inside the Mg matrix and there is no detachment of reinforcement.

The aim of this work is the development of Cu-Al2O3 composites of copper Cu-ETP matrix composite materials reinforced by 20 and 30

vol.% Al2O3 particles and study of some chosen physical properties. Squeeze casting technique of porous compacts with liquid copper

was applied at the pressure of 110 MPa. Introduction of alumina particles into copper matrix affected on the significant increase of

hardness and in the case of Cu-30 vol. % of alumina particles to 128 HBW. Electrical resistivity was strongly affected by the ceramic

alumina particles and addition of 20 vol. % of particles caused diminishing of electrical conductivity to 20 S/m (34.5% IACS). Thermal

conductivity tests were performed applying two methods and it was ascertained that this parameter strongly depends on the ceramic

particles content, diminishing it to 100 Wm-1K-1 for the composite material containing 30 vol.% of ceramic particles comparing to 400

Wm-1K-1 for the unreinforced copper. Microstructural analysis was carried out using SEM microscopy and indicates that Al2O3 particles

are homogeneously distributed in the copper matrix. EDS analysis shows remains of silicon on the surface of ceramic particles after

binding agent used during preparation of ceramic preforms.

The quality of the squeeze castings is significantly affected by secondary dendrite arm spacing, which is influenced by squeeze cast input

parameters. The relationships of secondary dendrite arm spacing with the input parameters, namely time delay, pressure duration, squeeze

pressure, pouring and die temperatures are complex in nature. The present research work focuses on the development of input-output

relationships using fuzzy logic approach. In fuzzy logic approach, squeeze cast process variables are expressed as a function of input

parameters and secondary dendrite arm spacing is expressed as an output parameter. It is important to note that two fuzzy logic based

approaches have been developed for the said problem. The first approach deals with the manually constructed mamdani based fuzzy

system and the second approach deals with automatic evolution of the Takagi and Sugeno’s fuzzy system. It is important to note that the

performance of the developed models is tested for both linear and non-linear type membership functions. In addition the developed models

were compared with the ten test cases which are different from those of training data. The developed fuzzy systems eliminates the need of

a number of trials in selection of most influential squeeze cast process parameters. This will reduce time and cost of trial experimentations.

The results showed that, all the developed models can be effectively used for making prediction. Further, the present research work will

help foundrymen to select parameters in squeeze casting to obtain the desired quality casting without much of time and resource

consuming.

This paper describes the possibility of using very short periods of solution annealing in the heat treatment of unmodified hypoeutectic silumin alloy AlSi7Mg0,3 casted by method of casting with crystallization under pressure with forced convection (direct squeeze casting process). Castings prepared at different casting parameters were subjected to special heat treatment called SST (Silicon Spheroidization Treatment), which were originally used only for the modified silumin alloys to spheroidization of eutectic silicon. Temperature holding time in solution annealing of T6 heat treatment is limited in the SST process to only a few minutes. It was studied the effect of casting parameters and periods of solution annealing on ultimate strength, yield strength, and especially ductility that in the unmodified silumin alloy castings is relatively low.

The paper deals with squeeze casting technology. For this research a direct squeeze casting method has been chosen. The influence of process parameters variation (casting temperature, mold temperature, pressure) on mechanical properties and structure will be observed. The thicknesses of the individual walls were selected based on the use of preferred numbers and series of preferred numbers (STN ISO 17) with the sequence of 3.15, 4.00, 5.00, 6.00 and 8.00 mm. The width of each wall was 22 mm with a length of 100 mm. As an experimental material was chosen the AlSi12 and AlSi7Mg0.3 alloys. The mechanical properties (UTS, E) for individual casting parameters and their individual areas of different thicknesses were evaluated. In the structure the influence of pressure on the change of the eutectic morphology, the change of the volume of eutectic and the primary alpha phase, the effect of the pressure on the more fine-grain and the regularization of the structure were evaluated.

The paper deals with the effect of heating of various prepared batch materials into semisolid state with subsequent solidification of the cast under pressure. The investigated material was a subeutectic aluminium alloy AlSi7Mg0.3. The heating temperature to the semisolid was chosen at 50% liquid phase. The used material was prepared in a variety of ways: heat treatment, inoculation and by squeeze casting. Also the influence of the initial state of material on inheritance of mechanical properties and microstructure was observed. The pressure was 100 MPa. Effect on the resulting casting structure, alpha phase distribution and eutectic silicon was observed. By using semisolid squeeze casting process the mechanical properties and microstructures of the casts has changed. The final microstructure of the casts is very similar to the microstructure that can be reached by technology of thixocasting. The mechanical properties by using semisolid squeeze casting has been increased except the heat treated material.

The fluidity is the term to determine the materials ability to fill the mold cavity properly. Fluidity is complex property with many variables. Up to this date, there is no methodology for defining the fluidity in a semisolid material state. Submitted paper deals with the proposal of a new method designed for aluminium alloy fluidity evaluation in semi-solid state trough the design of the layered construction die. Die will be primary used for fluidity tests of semi-solid squeeze casted aluminium alloy and to observe the pressing force flow by mentioned casting technology. The modularity consists of possibility to change each die segment. In the experiment the die design was evaluated by simulation in ProCAST 11.5 and by production of experimental castings. The die was made by laser cutting technology from construction steel S355JR. Experimental material was aluminium alloy AlSi7Mg0.3. The temperature of the semisolid state was chosen to achieve 35% of solid phase. The result of next study should be a selected parameters observation and their effect on the fluidity of aluminium alloy in semi-solid state. This will be very important step to determine the optimal conditions to achieve a castings with certain wall thickness produced by the method of semi-solid squeeze casting.

The near net shaped manufacturing ability of squeeze casting process requiresto set the process variable combinations at their optimal

levels to obtain both aesthetic appearance and internal soundness of the cast parts. The aesthetic and internal soundness of cast parts deal

with surface roughness and tensile strength those can readily put the part in service without the requirement of costly secondary

manufacturing processes (like polishing, shot blasting, plating, hear treatment etc.). It is difficult to determine the levels of the process

variable (that is, pressure duration, squeeze pressure, pouring temperature and die temperature) combinations for extreme values of the

responses (that is, surface roughness, yield strength and ultimate tensile strength) due to conflicting requirements. In the present

manuscript, three population based search and optimization methods, namely genetic algorithm (GA), particle swarm optimization (PSO)

and multi-objective particle swarm optimization based on crowding distance (MOPSO-CD) methods have been used to optimize multiple

outputs simultaneously. Further, validation test has been conducted for the optimal casting conditions suggested by GA, PSO and

MOPSO-CD. The results showed that PSO outperformed GA with regard to computation time.