A novel heat-resistant Al-Si-Cu-Ni-Mg base material synergistically strengthened by Ni-rich intermetallics and nano-AlNp microskeletons

In this work, nano-AlN particle (nano-AlNp) microskeletons were introduced into an Al-Si-Cu-Ni-Mg alloy by Al-8AlN master alloy in which the nano-AlNp reinforcements connect with each other to form three-dimensional networks. It is found that these nano-AlNp microskeletons mainly distribute in the binary Al-Si eutectic zones resulting in flaky eutectic Si phases being modified to particulates. Meanwhile, the microskeletons strengthen the matrix synergistically with semi-continuous Ni-rich intermetallics in three dimensions. The tensile mechanical properties, micro-hardness and thermal expansion properties of the alloy at different temperatures are significantly improved. Especially, the ultimate tensile strength (UTS) at 350 degrees C increases from 85 MPa to 106 MPa, rising by 24.7%, which is ascribed to nano-AlNp microskeletons assisting intermetallics with undertaking mechanical loading, and to the modification of eutectic Si phases to reduce the stress concentration at elevated temperatures. (C) 2018 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.