Effect of Ti and B additions as powder and preliminary alloy with Al-Si alloy on microstructure and mechanical properties of AlSi9Mg alloy intended for parts of agricultural machinery
2021
Lipinski, T., University of Warmia and Mazury in Olsztyn (Poland) | Karpisz, D., Cracow Univ. of Technology (Poland)
Foundry aluminium silicon alloys are widely used in various industries. In their unmodified state, they are not used for construction materials. Their use is possible after improving the unfavourable microstructure. Initially, the microstructure of hypoeutectic silumins is composed of a large primary α-phase and large, sharpshaped eutectic silicon grains. This phase creates microstructural notches. This microstructure is the reason for the low mechanical properties of the alloy. Increasing the properties of hypoeutectic silumins can be achieved, inter alia, by introducing chemical additives into the alloy, which refine the microstructure. There are reports in the literature on the use of various chemical compounds and technologies aimed at fragmenting the microstructure. A new approach is the modification process using a homogeneous modifier. This process does not introduce new alloying elements into the alloys. However, this process did not fragment the primary α-phase. The paper presents the results of AlSi9Mg alloy modification with AlSi9Mg alloy and boron and titanium. The test results confirm the effectiveness of the applied treatment. After it was carried out, the α + β eutectic and the primary α phase were fragmented. These changes, represented by the fragmentation of the microstructure, turned out to be correlated with an increase in the tensile strength of the alloy and its plasticity. The highest mechanical parameters (Rm = 195 MPa and A = 6.5%) were obtained for the alloy with 0.6% Al-Si + 0.15% Ti + 0.06% B.
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