آلياژسازي درجاي آلياژ Al-5%Cu به روش ذوب بستر پودر با ليزر و ارزيابي خواص مكانيكي

In this research, an aluminum alloy with 5% copper by weight (Al-5Cu) was developed via in-situ alloying using Laser Powder Bed Fusion (LPBF). This chemical composition was chosen due to its commercial an‎d practical nature in developing advanced 2000-series alloys, which can serve as a foundation for producing ultra-high-strength alloys. The objective of this study was to obtain comprehensive information on suitable processing parameters for fabricating this alloy an‎d to eva‎luate its mechanical performance in both as-built an‎d after precipitation hardening heat treatment conditions. Initially, the constituent metallic elements of the alloy were mixed using a combination of ball milling an‎d direct powder blending. Subsequently, the fabrication of various samples was carried out in two series. After determining the optimal parameters for producing dense, crack-free samples, simple compression an‎d tensile test specimens were fabricated. Furthermore, given the significant structural differences between parts produced via LPBF an‎d conventional casting, the most appropriate heat treatment cycle for this alloy was designed, eva‎luated, an‎d determined to enhance its mechanical properties. Additionally, the microhardness of the samples was eva‎luated at different stages an‎d compared with LPBF-produced pure aluminum. The results indicated that at high scan speeds, despite achieving a relative density of 99.8%, extensive solidification cracks formed in the sample structure. By modifying the process parameters an‎d significantly reducing the scan speed to 100 mm/s, the thermal gradient was moderated, resulting in fully dense, crack-free samples. Moreover, the identification of the intermetallic Al₂Cu phase via X-ray diffraction confirmed the success of the in-situ alloying process. Finally, artificial aging at 190°C for 12.5 hours (following 3 hours of solution treatment) led to a peak hardness of 101 HV, representing an increase of over 200% compared to pure aluminum. In the eva‎luation of mechanical properties, the optimized samples recorded an average compressive yield strength of 208 MPa an‎d an ultimate tensile strength of 259 MPa, demonstrating a significant improvement in strength compared to traditional casting methods. This enhancement in properties is attributed to the ultra-fine cellular microstructure resulting from rapid solidification an‎d the uniform distribution of strengthening precipitates after heat treatment. Furthermore, the analysis of asymmetric tensile an‎d compressive behavior revealed that microscopic pores close during compressive loading, leading to higher recorded yield strength. In summary, the process window obtained in this research can serve as a precise guide for achieving stronger alloys within this material family

علي مالكي , محسن بدرسماي

محسن صفوي , محمد آرام فرد