Study On The Preparation Of AlMgB₁₄ Doped With Different Oxide And Its Cutting Performance

AlMgB₁₄ has the advantages of high hardness,good wear resistance,good resistance to high temperature oxidation,low coefficient of friction.However,the lower toughness greatly restricts its application in industry.In order to improve the mechanical properties,Y₂O₃,Al₂O₃ and Mg O oxides have been doped AlMg B₁₄.The effect of addition of Y₂O₃,Al₂O₃ and MgO oxides on mechanical properties and microstructure has been investigated.At the same time,the AlMgB₁₄ turning inserts were prepared to cut gray cast iron,and the failure modes and wear mechanism of the AlMgB₁₄ tool were studied though cutting test.First,AlMgB₁₄ powder was prepared under the protection of Ar atmosphere.The effects of hot-press temperature and AlMgB₁₄ powder size on the microstructure and properties of AlMgB₁₄ were studied.The results show that the density and hardness of AlMgB₁₄ is increase with the increase of hot-pressing temperature.Under the temperature of 1600°C and pressure of 50 MPa,the density reaches 97.64%,the hardness is about28GPa.With the increase of milling time,the particle size of AlMg B₁₄4 powder is decreased,and the density of hot pressed AlMgB₁₄ increased,but the hardness is decreased and the fracture toughness increased.The density,hardness and fracture toughness of AlMgB₁₄ increase first and then decrease with the addition of Y₂O₃.When 1.2wt.%Y₂O₃ is added,the average hardness of the material reaches about 30 GPa and the average fracture toughness reaches 3.6 MPa.m^1/2.When Y₂O₃,Al₂O₃ and MgO oxides were doped,the hardness and fracture toughness of the AlMgB₁₄ material prepared by hot pressing are increased first and then decreased.When1.8wt.%Y₂O₃,0.9wt%Al₂O₃ and 0.9wt%MgO were added,the hardness of the AlMgB₁₄material owns the highest,hardness of 30.5GPa,and the fracture toughness was3.2MPam^1/2.The turning inserts with the materials of AlMgB₁₄,AlMgB₁₄-Y₂O₃ and AlMgB₁₄-Y₂O₃-Al₂O₃–MgO were prepared respectively.The cutting performance on HT250 grey cast iron was tested.It was found that AlMgB₁₄-Y₂O₃-Al₂O₃-MgO owns a lighter wear on flank face in comparison with AlMgB₁₄ and AlMgB₁₄-Y₂O₃.The rake face of the tool is easy to adhere to cast iron,and the flank face is susceptible to chipping and abrasion.