Search

This study focuses on the additive manufacturing technique of selective laser melting (SLM) to produce Ti-6Al-4V-Zn titanium alloy. The addition of zinc at 0.3 wt.% was investigated to improve the strength and ductility of SLM Ti-6Al-4V alloys. The microstructure and mechanical properties were analyzed using different vacuum heat treatment processes, with the 800-4-FC specimen exhibiting the most favorable overall mechanical properties. Additionally, zinc serves as a stabilizing element for the β phase, enhancing the resistance to particle erosion and corrosion impedance of Ti-6Al-4V-Zn alloy. Furthermore, the incorporation of trace amounts of Zn imparts improved impact toughness and stabilized high-temperature tensile mechanical properties to SLM Ti-6Al-4V-Zn alloy. The data obtained serve as valuable references for the application of SLM-64Ti. [ABSTRACT FROM AUTHOR]

In this study, trace quantities of silver, palladium, and gold were added to 5 N pure copper wires to prepare microalloyed copper (MAC) wires. The mechanical properties and electrical fatigue mechanisms of original wires and wire bonding specimens were compared to assess the differences between MAC and Au/Pd-coated copper (CPA) wires. The results indicate that the solid-solution strengthening achieved by the addition of trace alloy elements improved the microhardness and tensile properties of the wires; thus, the overall mechanical properties of the MAC wires were superior to those of a CPA wire. Moreover, after wire bonding, the MAC wires exhibited a higher first bond strength than the CPA wire. In terms of electrical properties, the addition of trace alloying elements increased resistance marginally, which resulted in MAC wires with higher dynamic resistance than the CPA wire in the early stage of electrification. At high currents, CPA wires are affected by Joule heat. The palladium atoms in the coating layer diffuse into the wire matrix, which causes the resistance to increase rapidly and thus results in a decreased fusing current. In a power cycling test, the coefficients of thermal expansion of the coating layers were different from that of the wire; thus, the CPA wire was susceptible to thermal fatigue, which led to its failure. The MAC wires had a higher power cycle life than the CPA wire. Because of their superior mechanical and electrical properties, MAC wires can replace CPA wires in the electronic packaging industry. [ABSTRACT FROM AUTHOR]

• The microstructure evolution of heat-treated SLM Al-Ni-Cu-Fe-Zr-Sc specimens was obtained. • The phase transformation of the heat-treated specimen was investigated. • The elemental composition of the bimodal microstructure was obtained. • The nanoprecipitation in the fine-grained region was investigated to clarify the precipitation mechanism. The novel selective laser melting (SLM) Al-Ni-Cu-Fe-Zr-Sc alloy has high temperature stability, but the segregation of the melting pool boundary limits its potential applications. Because conventional heat treatment with a solid solution at 530 °C is inappropriate for the SLM Al-Ni-Cu-Fe-Zr-Sc alloy, this study used hyper-high-temperature solid-solution treatment at three temperatures (560, 570, and 580 °C for 1 h) to investigate the evolution of the melting pool structure. An artificial aging treatment was applied at 175 °C for 6 h to investigate the precipitation mechanism. The results indicated that as-printed presented a bimodal microstructure consisting of a coarse-grained (CG) region and a fine-grained (FG) region. The hyper-high-temperature solid-solution treatment promoted the decomposition of the melting pool boundary and expansion of FG region. The FG region was composed of Ni-, Cu-, and Fe-rich equiaxed grains. After aging treatment, Al 9 Fe(Cu)Ni and Al 3 (Sc, Zr) nano-scale strengthening phases could be found in the FG region. The decomposition of the melting pool boundary, bimodal microstructure, and nano-scale phases can strengthen the matrix and increase hardness. In addition, the mechanism of element diffusion in melting pool was also explored to confirm that heat treatment can reduce material deterioration caused by boundary precipitation. These characteristics mitigate the disadvantages of the SLM Al-Ni-Cu-Fe-Zr-Sc alloy in terms of its strength directionality and establish its potential for use in aerospace applications. [ABSTRACT FROM AUTHOR]

Metal powder metallurgy (PM) is widely utilized in the tool and automotive industries due to its near-net forming advantages. While PM aluminum alloys have been explored in numerous studies, their practical engineering applications are still limited. Thus, this research delves into the nuanced aspects of PM Al-Si-Mg-Fe alloy. By employing hot-rolled dynamic recrystallization to control the metallurgical texture and introducing T6 treatment to refine the microstructure. These optimizations aim to enhance the properties of PM aluminum alloy materials. Results revealed that grain coarsening in the PM Al-Si-Mg-Fe alloy hampers the grain boundary strengthening effects, thus limiting the strength. Moreover, the solid-solution treatment applied to the PM specimens efficiently disperses silicon particles within the matrix, preventing the aggregation of silicon particles and the associated brittle effect caused by interface peeling. By implementing a three-stage process, sintering-rolling-T6 treatment, the rolled-T6 exhibited impressive tensile strength (291 MPa) and ductility (17 %), highlighting the excellent engineering applicability of PM Al-alloys. TEM analysis confirmed the presence of nanoprecipitation Al 3 Mg and Al 9 Fe 2 hard components within the matrix, contributing to the strength enhancement. These findings not only represent a significant milestone in the advancement but also provide valuable references for engineering applications in the field of PM Al-alloys. • PM technology enhances Al-Si-Mg-Fe alloy applications. • Three-stage process optimizes microstructure and properties. • Microstructural effects and phase distribution are compared. • Reveals Al 9 Fe 2 and Al(Si) 3 Mg strengthening mechanisms. [ABSTRACT FROM AUTHOR]