Microstructure, mechanical properties and multiphase synergistic strengthening mechanisms of a novel laser additive manufactured AlNi6TiZr alloy

Abstract

In this work, selective laser melting (SLM) process is used to prepare the AlNi6TiZr alloy. By analyzing the printing quality and mechanical properties of the printed specimens with different process parameters, the SLM forming window of AlNi6TiZr is obtained. The relative density of the sample printed with 270 W-1100 mm/s (laser energy density: 82 J/mm3) reaches 99.7%, exhibiting excellent mechanical properties (yield strength (YS): 421.7 MPa; ultimate tensile strength (UTS): 480.4 MPa). After an aging treatment of 325 °C-12 h, the YS and UTS of the sample increased to 494 MPa and 550.7 MPa, respectively. Adding Ni, Ti, and Zr components promoted the generation of multi-phase precipitates in the Al alloy and improved the synergistic strengthening effect of multi-phases. The hard-shell structure (HSS) formed by the Al3Ni phase at the grain boundary significantly strengthened the grain boundary strength. The precipitated Al3(Ti, Zr) phases at the grain boundaries prevent grain growth and dislocation movement. The Al3Ni and Al3(Ti, Zr) phases have good thermal stability that can still maintain excellent enhancement effects at high temperature. AlNi6TiZr alloy has great application prospects in medium and high-temperature environments.