The presented work discusses the influence of material of foundry mould on the effect of modification of AlSi11 alloy. For this purpose castings were produced in moulds made of four various materials. Castings of the first type were cast in a metal die, the second ones in the conventional mould of bentonite-bound sand, those of the third type in the sand mould with oil binder, the last ones in a shell mould where phenol-formaldehyde resin was applied as a binder. All the castings were made of AlSi11 alloy modified with strontium. For a purpose of comparison also castings made of the non-modified alloy were produced. The castings were examined with regard to their microstructures. The performed investigations point out that the addition of strontium master alloy results in refining of the alloy structure, particularly of the α-phase, causes some morphological changes in the alloy and the refinement of eutectics. The advantageous influence of modifier on the structure of the examined silumin was observed particularly in the case of alloy cast either in the conventional oil-bound sand mould or in the shell mould. The non-modified alloy cast into a metal die exhibits a structure similar to those of modified alloy solidifying in the other moulds. The improvement in both tensile strength and unit elongation suggests that the modification was carried out correctly. The best mechanical properties were found for the alloy cast in a metal die, both with and without modification treatment.

The presented work deals with the influence of the addition of soft graphite particles on the abrasive wear of composite reinforced with

hard SiC particles. The discussed hybrid composites were produced by stirring the liquid alloy and simultaneous adding the mixture of

particles. The adequately prepared suspension was gravity cast into a metal die. Both the composite castings obtained in this way and the

comparative castings produced of the pure matrix alloy were examined for the abrasive wear behaviour. Photomacrographs of the sliding

surfaces of the examined composites were taken, and also the hardness measurements were carried out. It was found that even a small

addition of Cgr particles influences positively the tribological properties of the examined composite materials, protecting the abraded

surface from the destructive action of silicon carbide particles. The work presents also the results of hardness measurements which confirm

that the composite material hardness increases with an increase in the volume fraction of hard reinforcing particles.

The presented work describes the results of examination of the mechanical properties of castings made either of AlSi9Mg alloy matrix

composite reinforced with short carbon fibre or of the pure AlSi9Mg alloy. The tensile strength, the yield strength, Young’s modulus, and

the unit elongation were examined both for initial castings and for castings made of the remelted composite or AlSi9Mg alloy. After

preparing metallographic specimens, the structure of the remelted materials was assessed. A few non-metallic inclusions were observed in

the structure of the remelted composite, not occurring in the initial castings. Mechanical testing revealed that all the examined properties of

the initial composite material exceed those of the non-reinforced matrix. A decrease in mechanical properties was stated both for the metal

matrix and for the composite after the remelting process, but this decrease was so slight that it either does not preclude them from further

use or does not restrict the range of their application.

The paper presents the possibility of application of the developed computer script which allows the assessment of non-equilibrium

solidification of binary alloys in the ThermoCalc program. The script makes use of databases and calculation procedures of the POLY-3

module. A solidification model including diffusion in the solid state, developed by Wołczyński, is used to describe the non-equilibrium

solidification. The model takes into account the influence of the degree of solute segregation on the solidification process by applying the

so-called back-diffusion parameter. The core of the script is the iteration procedure with implemented model equation. The possibility of

application of the presented calculation method is illustrated on the example of the Cr-30% Ni alloy. Computer simulations carried out

with use of the developed script allow to determine the influence of the back-diffusion parameter on the course of solidification curves,

solidus temperature, phase composition of the alloy and the fraction of each phase after the solidification completion, the profile of solute

concentration in liquid during solidification process, the average solute concentration in solid phase at the eutectic temperature and many

other quantities which are usually calculated in the ThermoCalc program.

The work presents the results of examinations concerning the influence of various amounts of home scrap additions on the porosity of

castings made of MgAl9Zn1 alloy. The fraction of home scrap in the metal charge ranged from 0 to 100%. Castings were pressure cast by

means of the hot-chamber pressure die casting machine under the industrial conditions in one of the domestic foundries. Additionally, for

the purpose of comparison, the porosity of specimens cut out directly of the MgAl9Zn1 ingot alloy was also determined. The examinations

consisted in the qualitative assessment of porosity by means of the optical microscopy and its quantitative determination by the method of

weighting specimens in air and in water. It was found during the examination that the porosity of castings decreases with an increase in the

home scrap fraction in the metal charge. The qualitative examinations confirmed the beneficial influence of the increased home scrap

fraction on the porosity of castings. It was concluded that the reusing of home scrap in a foundry can be a good way of reduction of costs

related to the production of pressure castings.

The results of examinations of the influence of titanium-boron inoculant on the solidification, the microstructure, and the mechanical

properties of AlZn20 alloy are presented. The examinations were carried out for specimens cast both of the non-modified and the

inoculated alloy. There were assessed changes in the alloy overcooling during the first stage of solidification due to the nuclei-forming

influence of the inoculant. The results of quantitative metallographic measurements concerning the refinement of the grain structure of

casting produced in sand moulds are presented. The cooling rate sensitivity of the alloy was proved by revealing changes in morphology of

the α-phase primary crystals. Differences in mechanical properties resulting from the applied casting method and optional inoculation were

evaluated.

The work deals with the influence of change in the filling conditions of the ceramic moulds with plaster binder on the presence of gaseous

porosity and the microstructure of the achieved test castings with graded wall thickness. Castings made of EN AC-44000 alloy, produced

either by gravity casting, or by gravity casting with negative pressure generated around the mould (according to the Vacumetal

technology), or by counter-gravity casting were compared. The results of examinations concerning the density of the produced castings

indicate that no significant change in porosity was found. The increased size of silicon crystals was found for the increased wall

thicknesses due to the slower cooling and solidification of castings.

The presented work is aimed to deal with the influence of changes in the value of negative (relative) pressure maintained in the die

cavity of pressure die casting machine on the surface quality of pressure castings. The examinations were held by means of the

modified Vertacast pressure die casting machine equipped with a vacuum system. Castings were produced for the parameters selected

on the basis of previous experiments, i.e. for the plunger velocity in the second stage of injection at the level of 4 m/s, the pouring

temperature of the alloy equal to 640°C, and the die temperature of 150°C. The examinations were carried on for three selected values

of negative gauge pressure: - 0.03, - 0.05, and - 0.07 MPa. The quality of casting was evaluated by comparing the results of the surface

roughness measurements performed for randomly selected castings. The surface roughness was measured by means of Hommel Tester

T1000. After a series of measurements it was found that the smoothest surface is exhibited by castings produced at negative gauge

pressure value of - 0.07 MPa.

The paper presents the results of investigations concerning the influence of negative (relative) pressure in the die cavity of high pressure

die casting machine on the porosity of castings made of AlSi9Cu3 alloy. Examinations were carried out for the VertaCast cold chamber

vertical pressure die casting machine equipped with a vacuum system. Experiments were performed for three values of the applied gauge

pressure: -0.3 bar, -0.5 bar, and -0.7 bar, at constant values of other technological parameters, selected during the formerly carried initial

experiments. Porosity of castings was assessed on the basis of microstructure observation and the density measurements performed by the

method of hydrostatic weighing. The performed investigation allowed to find out that – for the examined pressure range – the porosity of

castings decreases linearly with an increase in the absolute value of negative pressure applied to the die cavity. The negative pressure value

of -0.7 bar allows to produce castings exhibiting porosity value less than 1%. Large blowholes arisen probably by occlusion of gaseous

phase during the injection of metal into the die cavity, were found in castings produced at the negative pressure value of -0.3 bar. These

blowholes are placed mostly in regions of local thermal centres and often accompanied by the discontinuities in the form of interdendritic

shrinkage micro-porosity. It was concluded that the high quality AlSi9Cu3 alloy castings able to work in elevated temperatures can be

achieved for the absolute value of the negative pressure applied to the die cavity greater than 0.5 bar at the applied set of other parameters

of pressure die casting machine work.

The performed examinations concerning the process of filling the plaster ceramic moulds with aluminium alloys allowed to assess the

influence of various methods of introducing the metal into the mould cavity on the macro- and microstructure of the obtained experimental

castings. The comparison was performed for castings with graded wall thickness made either of EN AC-44000 alloy or of EN AC-46000

alloy, produced either by gravity casting, or by gravity casting with negative pressure generated around the mould (according to the

Vacumetal technology), or by counter-gravity casting. It was found that the silicon crystals grow in size with an increase in wall thickness

due to the slower cooling and solidification of castings.

The paper presents the method of preparing a composite slurry composed of AlSi11 alloy matrix and 10 vol.% of SiC particles, as well as

the method of its high-pressure die casting and the measurement results concerning the castability of the obtained composite. Composite

castings were produced at various values of the piston velocity in the second stage of injection, diverse intensification pressure values, and

various injection gate width values. There were found the regression equations describing the change of castability of the examined

composite as a function of pressure die casting process parameters. The conclusion gives the analysis and the interpretation of the obtained

results.

A numerical model of binary alloy crystallization, based on the cellular automaton technique, is presented. The model allows to follow the

crystallization front movement and to generate the images of evolution of the dendritic structures during the solidification of a binary

alloy. The mathematic description of the model takes into account the proceeding thermal, diffusive, and surface phenomena. There are

presented the results of numerical simulations concerning the multi-dendritic growth of solid phase along with the accompanying changes

in the alloying element concentration field during the solidification of Al + 5% wt. Mg alloy. The model structure of the solidified casting

was achieved and compared with the actual structure of a die casting. The dendrite interaction was studied with respect to its influence on

the generation and growth of the primary and secondary dendrite arms and on the evolution of solute segregation both in the liquid and in

the solid state during the crystallization of the examined alloy. The morphology of a single, free-growing dendritic crystal was also

modelled. The performed investigations and analyses allowed to state e.g. that the developed numerical model correctly describes the

actual evolution of the dendritic structure under the non-equilibrium conditions and provides for obtaining the qualitatively correct results

of simulation of the crystallization process.

The results of castability and structures researches of two nickel base alloys - Ceranium CN and Magnum AN applied on casting of the crowns and dental bridges are presented. Studies were carried out on the alloys cast under the centrifugal force to the moulds made by the lost wax method using production line of ROKO. Having regard to a specific technology of casting and possibility of ROKO production line, to the estimation of alloys castability a spiral test was adjusted with a 0,8 mm and a 2,5 mm diameter of test casting. Measuriements executed on a 20 test castings allowed to establish, that castability of Magnum AN alloy was 65 % greater than castability of Ceranium NC alloy. The results of thermodynamics calculations of the equilibrium and nonequilibrium crystallization (Scheil model) of the investigated alloys are presented too. The characteristic temperatures of phase transformation and forecast phase composition of alloys for both kind of crystallization were calculated. It is established after structural supervisions, that the investigated alloys crystallize in dendryte form and in centrifugal casting conditions have cooling rate sensivity and inclination to texture structure forming in outmost layer of casting. Phase composition of alloys corresponds to the results of thermodynamics calculations of the nonequilibrium crystallization conditions.

The work presents the investigation results concerning the structure of composite pressure die castings with AlSi11 alloy matrix reinforced

with SiC particles. Examination has been held for composites containing 10 and 20 volume percent of SiC particles. The arrangement of

the reinforcing particles within the matrix has been qualitatively assessed in specimens cut out of the castings. The index of distribution

was determined on the basis of particle count in elementary measuring fields. The tensile strength, the yield point and elongation of the

obtained composite were measured. Composite castings were produced at various values of the piston velocity in the second stage of

injection, diverse intensification pressure values, and various injection gate width values. The regression equation describing the change of

the considered arrangement particles index and mechanical properties were found as a function of the pressure die casting parameters. The

infuence of particle arrangement in composite matrix on mechanical properties these material was examined and the functions of

correlations between values were obtained. The conclusion gives the analysis and the interpretation of the obtained results.

The work presents the results of examinations concerning the influence of various amounts of home scrap additions on the properties of

castings made of MgAl9Zn1 alloy. The fraction of home scrap in the metal charge ranged from 0 to 100%. Castings were pressure cast by

means of the hot-chamber pressure die casting machine under the industrial conditions in one of the domestic foundries. The examinations

consisted in the determination of the following properties: tensile strength Rm, yield strength Rp0.2, and the unit elongation A5, all being

measured during the static tensile test. Also, the hardness measurements were taken by the Brinell method. It was found that the

mechanical properties (mainly the strength properties) are being improved up to the home scrap fraction of 50%. Their values were

increased by about 30% over this range. Further rise in the home scrap content, however, brought a definite decrease in these properties.

The unit elongation A5 exhibited continual decrease with an increase in the home scrap fraction in the metal charge. A large growth of

hardness was noticed for the home scrap fraction increasing up to the value of 50%. Further increasing the home scrap percentage,

however, did not result in a significant rise of the hardness value any more.