| As Al-Cu alloy has good performance in high and low temperature mechanical properties and wear resistance,it has been widely used in aerospace,construction manufacturing and equipment and other fields.The Cu content has an important effect on the mechanical properties of Al-Cu alloy.However,the increase of Cu content is beneficial to improve the high temperature strength and wear resistance of Al-Cu alloy.Therefore,the influence of high Cu content on the tensile properties and wear resistance of Al-Cu alloy was systematically studied in this paper.The effects of liquid die-casting and rheological die-casting processes on the tensile properties and wear resistance of the castings were studied.Al-Cu alloy die-casting samples with Cu content of 5%-20%were prepared,and the variation of tensile properties with Cu content and die casting process was systematically studied.The experimental results of mechanical properties show that:With the increase of Cu content,the tensile strength of Al-Cu alloy increased and the elongation decreased at room temperature.With the increase of tensile test temperature,the tensile strength of samples generally decreased,and the elongation generally increased.When the temperature of the tensile test increased from 200°C to 300?,the tensile strength and elongation of the sample changed mostly;At 300?,the tensile strength and elongation of Al-20Cu alloy sample can reach 144MPa and 4.14%.In addition,with the increase of tensile test temperature from room temperature to 300?,the fracture form at the edge of the fracture of Al-5Cu sample was changed from the mixture of dimple and quasi-cleavage fracture to dimple fracture,and the fracture form at the edge of the fracture of Al-20Cu samples were changed from quasi-cleavage fracture to the mixture of dimple and quasi-cleavage fracture.By comparing the mechanical properties of Al-15Cu tensile samples with different casting temperatures,it was found that the density of the tensile samples was the highest when the casting temperature was 610?and the electromagnetic stirring was applied.At room temperature and 300?,its tensile strength and elongation were higher than those of other rheo-cast tensile samples.At 300?,its tensile strength could reach 118MPa,and the elongation reached 7.99%.The macroscopic fracture form also changed from the brittle fracture at room temperature to the ductile fracture at high temperature.The wear behavior and properties of cast Al-Cu alloy with 5%-20%Cu content under different compositions and loads were studied.The results showed that:with the increase of Cu content,the hardness of the worn samples increased from 59HB to 170HB,and the friction coefficient varied from 0.4 to 0.85 with the change of Cu content.The friction coefficient of the samples with high Cu content was larger and fluctuated greatly.With the increase of load,the friction coefficient decreased gradually;With the increase of Cu content,the specific wear rate of Al-Cu alloy samples decreased sharply at first and then tended to be gentle.The main wear mechanisms of Al-Cu alloys were adhesive wear and abrasive wear.For samples with low Cu content,adhesive wear was dominant,while samples with high Cu content were mainly abrasive wear.With the increase of load,the adhesive wear degree of the samples with low Cu content increased,and the abrasive wear degree of the samples with high Cu content increased.For the rheo-cast Al-15Cu alloy sample,with the increase of casting temperature,the hardness of rheo-cast Al-15Cu alloy samples increased gradually When the casting temperature was 615?and the electromagnetic stirring is applied,the hardness of the samples was the highest,which was 118HB.The friction coefficient and volume loss of the samples decreased with the increase of casting temperature.When the casting temperature was 615?and the electromagnetic stirring was applied,the wear resistance of the sample was the best,the average friction coefficient was 0.655,and the volume loss was 0.042mm~3. |
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