**1. Introduction**

Inconel 718 (IN718) is widely applied in aeronautics, astronautics, and energy industries because of its excellent corrosion resistance, oxidation resistance, weldability, and mechanical properties under circumstances like room temperature and elevated temperature. Its application area includes gas turbines, turbine blades, rocket engines, components for oil and gas extraction, and nuclear engineering [1–4]. IN718 is precipitation strengthened nickel-based superalloy which could be strengthened by precipitation of D022 γ" (Ni3Nb), L12 γ (Ni3(Al, Ti)), and D0a δ (Ni3Nb) in the γ matrix [5], thus could be imported in the engineering applications.

Additive manufacturing (AM) can reduce costs, save mold manufacturing costs, and create complex geometric shapes. It has been applied to various industries [6]. Selective laser melting (SLM) is classified as the family of AM technologies. SLM uses metal powder as raw material to be illuminated by a high-energy laser beam within a specified area. After the powder melts, it is rapidly solidified at high cooling rates [7–9].

Blades, turbines, and engines are often impacted by solid particle erosion wear, resulting in damage to pieces and equipment. Erosion wear is the phenomenon of gas or liquid-driven particles striking the surface of a material [10,11]. Few articles mention the particle erosion wear of nickel-based superalloys. Most of them concern their casting and forging [12–14]. We are interested in particle erosion resistance and the erosion induced phase transformation of 3D-printed IN718.

Particle erosion wear could induce phase transformation. This phenomenon has been confirmed by Al-Si-Mg alloy [15], austempered ductile iron (ADI) [16], 316 stainless steel [17], and even 3D-printed Ti-6Al-4V [18]. The heat generated by particle impact or strain helps dissolve a phase or form a new phase, further a ffecting the hardness and other mechanical properties.

Based on this, the purpose of this study is to investigate the microstructure and the mechanical properties of heat-treated SLM Inconel 718. To clarify the erosion-induced phase transformation mechanism and its e ffect on the material brittleness, we compared the particle erosion wear behavior of as-SLM Inconel 718 with those of three heat-treated specimens. These results have significant reference value for the aerospace industry.
