Experimental Study of Correlation of Mechanical Properties of Al-Si Casts Produced by Pressure Die Casting with Si/Fe/Mn Content and Their Mutual Mass Relations
Table 1
Characteristic, properties, and impact of chosen alloying elements [11, 12, 14–20].
Element
Characteristic
B
Content refines structure and increases electrical conductivity in technically clean aluminium due to precipitation of V, Cr, Mo, and Ti from solid solution
Bi
Alloying with this element improves mechanical machinability
Sb
It serves for improving of corrosion resistance in salty water solutions; in Al-Mg compositions decreases tendency to crack generation
Cr
Alloying with this element decreases susceptibility of grain growth in Al-Mg alloys; in hardenable alloys it increases hardening capacity
Cu
It decreases solidification shrinkage and enables thermal hardening; undesirable effect is a decrease in corrosion resistance; most often it is used along with Mg
Co
In some Al-Si alloys with Fe present, it is added to transform needle-shape phase rich in iron into sphere morphology; this improves strength and plastic properties
Fe
In Al-Si alloys, it occurs as an impurity; solubility in solid state is low (approx. 0.04%); due to this, it is present in structure as intermetallic compound with aluminium Al5FeSi; in Al-Cu alloys it creates intermetallic compound Al7FeCu2, thus reducing copper content in solid solution which leads to a decrease of strength properties
Mg
It is alloyed in order to increase strength properties by hardening formation of intermetallic compound Mg2Si; it deteriorates fluidity and improves machinability
Mn
It is alloyed into aluminium alloys in order to improve strength, to increase recrystallization temperature, to refine grains, to block grain growth in the case of its segregation in form of disperse precipitates, and to suppress iron segregation in lamellar form; for elimination of harmful iron influence, it is usually added in half content of the iron content
Mo
It is alloyed up to 0.3% in order to refine structure
Ni
It is alloyed in order to improve strength of Al-Cu, Al-Si alloys at higher temperatures; it improves corrosion resistance
Si
In Al-Si alloys, it is the main alloying element, presence of which improves casting properties; comparing with properties of pure aluminium, depending of silicium content, strength is increased
Ti
It is alloyed together with B in order to refine structure
