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Abstract The effect of V addition on the microstructure and mechanical properties of Cu-15Ni-8Sn alloy was systematically investigated in the present study. The results indicate that the significant grain refinement can be achieved by adding trace V content for Cu-15Ni-8Sn alloy, which is ascribed to the formation of V-bearing intermetallic compound. Besides, the addition of V also brings obvious change in the morphology around grain boundary. After solution treatment at 850 °C for 4 h, considerable Ni 3 V particles precipitate from the matrix, which can hinder the grain boundary migration and remain the grain refinement effect. Besides, it can also significantly influence the microstructure and its resulting mechanical properties of the alloy during the subsequent aging process. Moreover, it was found that, after aging treatment at 400 °C, Cu-15Ni-8Sn alloy can possess excellent softening resistance with an appropriate addition of V. Namely, it can maintain a high hardness and ultimate tensile strength with the extension of aging time. In addition, the grain refinement and the suppression of discontinuous precipitation by Ni 3 V particles are believed to be responsible for the improving strength. Especially, when aging for 4 h, the ultimate tensile strength increases from 899 MPa (Cu-15Ni-8Sn) to 990 MPa (Cu-15Ni-8Sn-0.4V). The optimal comprehensive performance can be obtained for Cu-15Ni-8Sn-0.4V alloy with a hardness (368 HV), ultimate tensile strength (990 MPa), electrical conductivity (8.03%IACS) when aging at 400 °C for 4 h. [ABSTRACT FROM AUTHOR]

Traditional phosphor bronzes have faced difficulties in terms of strengthening via heat treatment. In this study, a Cu-Sn-P-Ni-Si alloy with capability of precipitation strengthening was designed based on phase diagram calculations. After direct aging treatment, the mechanical properties of the Cu-8Sn-0.1P alloy exhibit minimal changes. However, significant strengthening was achieved in the Cu-Sn-P-Ni-Si alloy. Experimental results demonstrate that during the direct aging process, semi-coherent interfaces are formed between the precipitate phases and the matrix in Cu-8Sn-0.1P-1Ni-0.227Si alloy, resulting in significant performance enhancement. Specifically, the yield strength of the alloy was increased by approximately 39% after aging treatment. Crucially, the strengthening mechanism of the Cu-Sn-P-Ni-Si alloy and the formation mechanism of semi-coherent interfaces were elucidated. This work provides a method to significantly enhance the comprehensive performance of phosphor bronze without requiring any special additional manufacturing processes. The achievement of heat treatment strengthening of phosphor bronze without undergoing deformation processing will enhance its potential for application. • Heat treatment strengthening of phosphor bronze was achieved. • Semi-coherent interface was formed between precipitates and the matrix. • The properties of Cu–8Sn-0.1P–1Ni-0.227Si is significantly enhanced. • The primary strengthening mechanism in this work is precipitation strengthening. [ABSTRACT FROM AUTHOR]

The Cu-15Ni-8Sn-XZr (wt.%, X=0–0.7) alloys were prepared by vacuum melting, and their microstructural evolutions during the solidification and heat-treatment processes were systematically investigated as well as the corresponding mechanical properties. Zr addition could offer a significant effect on the dendritic morphology by controlling the constitutional supercooling in solidification front, and it also made the γ-phase more likely to form in the needlelike-shape rather than the lamellar-like shape in subsequent cooling process. After solution treatment, the Zr atoms with a low content of 0.1 wt% were completely solidly dissolved in the α-matrix. With its content increasing to 0.3 and 0.5 wt%, the existence form was changed into the nano-scale precipitation phase (Ni 5 Zr) and then to micron-scale segregation phase (Ni 4 SnZr). The presence of Zr could significantly extend the aging window of alloy and improve its mechanical properties by inhibiting the nucleation and growth of discontinuous precipitation (DP), and there was few DP even after 16 h aging. The optimal combination of properties was obtained for Cu-15Ni-8Sn-0.5Zr alloy aged at 673 K for 4–16 h, including a hardness of 330HB, ultimate tensile strength (UTS) of 980 MPa and electrical conductivity of 9%IACS. • Zr significantly inhibit the harmful DP but not the beneficial ordered phases, there is few DP even after 16 h aging. • The optimal property is obtained for 0.5Zr addition, for hardness >330HB, UTS >980MPa, electrical conductivity >9%IACS. • With Zr content increase, its existence form is changed from solid solute to nanoscale Ni5Zr, then to micronscale Ni4SnZr. [ABSTRACT FROM AUTHOR]

In this work, cold drawing deformation was applied aiming to achieve a good combination of strength and electrical conductivity of Cu–20Fe alloy, and also such underlying mechanisms for microstructure evolution and strengthening, as well as variation in conductivity were clarified. It is also found that both Cu matrix grains and Fe-rich dendrites can be significantly refined and transformed into fibrous structure with increasing of drawing strain. The average size of Cu grains and thickness of Fe fiber are 0.47 ± 0.05 μm and 25 ± 5 nm, respectively for alloy subjected to the drawing strain of η = 5.78. In addition, the Fe dendrites exhibit a strong <110> fiber texture, while the corresponding Cu matrix forms a <111> fiber texture. It is demonstrated that the excellent properties with the yield strength of 1173 MPa and the electrical conductivity of 41 %IACS can be reached for cold-drawn Cu–20Fe alloy. In addition, the quantitative analysis on strengthening contributions shows that the high strength of as-drawn Cu–20Fe alloy is dominantly originated from high-density Fe fibers. Meanwhile, the lower electrical conductivity is ascribed to the high solute Fe content and high-density Cu/Fe heterogeneous phase interface. • The microstructure evolution and properties of Cu–20Fe alloys at different drawing strains were clearly elucidated. • The Cu–Fe dual-phase co-deformation behavior during drawing deformation process was described. • A strengthening model of Cu–Fe dual phase alloy under severe plastic deformation was established. • The Cu–20Fe alloy achieves a good combination of mechanical and electrical properties at drawing strain of η = 5.78. [ABSTRACT FROM AUTHOR]

In the present study, an Al–Ni–Mg ternary reaction was used to provide an improved interfacial structure of carbon fiber reinforced Al-matrix (CF/Al) composites fabricated by a rapid process in open space. Driven by ternary reaction, better infiltration behavior of Al matrix can be obtained. With increasing Mg element addition, the ternary reaction was enhanced with the formation of Al–Ni–Mg IMCs with gradually larger size. When the value is 2.5 wt%, the relative density increases from 96.3% to 97.1%, and the crack density is reduced by 88.5% compared with those of Al-matrix composites due to the elimination of micro-defects. At the same time, the formation of IMCs with optimal size and distribution was obtained, which indicates the suitably Al/Ni interfacial state and provides effective load transfer and significant enhancement of the mechanical properties. The ultimate tensile strength (UTS) of the composites with Al-2.5 Mg matrix is 108 MPa, which is 18.7% higher than that of the corresponding matrix, and the improvement of UTS is the largest compared with that of the composites with 1.25 wt%, 3.75 wt%, and 5 wt% Mg element addition. [Display omitted] ● Al–Ni–Mg ternary interfacial reaction was applied to induce better infiltration behavior with lower crack density and larger relative density. ● Driven by ternary reaction, improved interfacial structure was provided with the formation of IMCs with optimal size and distribution. ● By adding 2.5 wt% Mg, optimal interfacial state was obtained with effective load transfer and significant enhanced mechanical properties. [ABSTRACT FROM AUTHOR]