Al-Si alloys are widely used in producing precise wear-resistant parts, such as air condition compressors, automobile engine pistons and cylinder bodies in automotive industry and machine-building industry due to the best cast ability among cast aluminum alloys. Especially, hypereutectic Al-Si alloys are rich in silicon. Therefore, they have some advantages such as small coefficient of heat expansion, good resistance to wear, high dimensional stability and lower casting cost.
At the same time, they have some disadvantages of lowering mechanical properties by primary crystal silicon as rough polygon or piece layers unless modified treatment is not enough in crystallization process because of high content of silicon.
Al alloys containing a trace of rare earth metal have high strength, hardness, wear resistance, corrosion resistance and electrical conductivity.
Preceding researches were mainly conducted on the effects of rare earth metal on the mechanical properties of Al-Si alloys.
Ri Hyon Mo, a researcher at the Faculty of Metal Engineering, has investigated the effects of Al-10RE master alloy as grain finer on the tensile strength, elongation percentage and resistance to wear of AiSi19Cu2주. Al-10RE master alloy was used as grain finer of AiSi19Cu2주.
The tensile strength, elongation percentage and resistance to wear of Al-Si hypereutectic cast alloy increase with increase in additive amount of Al-10RE master alloy up to 5%, but they decrease over 5%. After heat treatment, the tensile strength and elongation were 296MPa and 0.84%, respectively, when the additive amount of Al-10RE master alloy was 5%. They increase by 24.4% and 44.8% respectively more than AiSi19Cu2주 without addition of Al-10RE master alloy.
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