Effects of Nd on microstructure and mechanical properties of cast Al-Si-Cu-Ni-Mg piston alloys

Effects of Nd content on the microstructure and mechanical properties of gravity cast Al-12Si-4Cu-2Ni0.8Mg alloys are reported. Metallographic and image analysis techniques have been used to quantitatively examine the microstructural changes at different Nd contents. It is found that adding 0.2% Nd to the as-cast Al-12Si-4Cu-2Ni-0.8Mg alloys has little influence on tensile properties at ambient temperature, but improves them at elevated temperature. The optimal UTS is 118.5 MPa at 300 degrees C and 74.2 MPa at 350 degrees C. It is due to the disappearance of the unstable phases at high temperature such as theta-Al2Cu, gamma-Al7Cu4Ni and parts of Q-Al5Cu2Mg8Si6 and formation of the high melting block-like Nd-containing phases. (C) 2016 Elsevier B.V. All rights reserved.