The transformation behavior of Cu–8.0Ni–1.8Si–0.6Sn–0.15Mg alloy during isothermal heat treatment

Improvement in strength and thermal conductivity of powder metallurgy produced Cu–Ni–Si–Cr alloy by adjusting Ni/Si weight ratio and hot forging

“…4(b)), two kinds of Ni-Si intermetallic compounds could be identified: one is b-Ni 3 Si (a = 3.51 nm; space group: Pm 3m), as indicated by the black asterisks, and the other one is d-Ni 2 Si, which has an orthorhombic lattice of a = 0.703 nm, b = 0.499 nm, and c = 0.372 nm. The abovementioned Ni-Si intermetallic compounds precipitating in the Cu-Ni-Si-based alloy system have also been widely reported in various studies [7,12,15]. In addition, two variants of d-Ni 2 Si, with a mutually perpendicular orientation present in the copper matrix, can be seen in the SAED pattern, as indicated by the white arrows in Fig.…”

“…XRD profiles (see Fig. 3) and earlier studies indicate that the major micro-sized precipitates at the grain boundaries or in the grains were Cr 3 Si [13], Ni 2 Si [7,12,14] and Ni 31 S 12 [11]. Earlier studies also indicate that Cr/Si precipitates are more stable at higher temperatures than Ni/Si, which could prevent grain growth during the solution heat treatment.…”

“…However, up to now, the microstructure of the precipitation for the Cu-Ni-Si alloys with high Ni contents or high Ni/Si ratio has not been studied systematically. Only few articles [5,7,15,27] have been published to determine the microstructure of the precipitation for the Cu-Ni-Si alloys with high Ni contents (>6.0 wt.%). In this study, to provide an optimal balance of mechanical properties, reasonable thermal conductivity and fine grain, the composition of the P/M alloys designed essentially consists of a higher wt.% Ni (7.0 wt.%) and a higher Ni/Si ratio (around 4), with a third alloy element, Cr, added.…”

“…1,6] systems are good prospects for substitution for the toxic Be-Cu alloy. To provide sound mechanical and physical properties for mold application, the composition of these alloys essentially consists of about 6-8 wt.% Ni, about 1-2 wt.% Si and about 0.3-2.0 wt.% Cr [7,8].…”

Increasing toughness by promoting discontinuous precipitation in Cu–Ni–Si alloys

“…Many commercial Cu-Ni-Si alloys utilize the thermomechanical treatment of solution treatment and ageing to introduce continuous precipitation (CP) of Ni 2 Si particles in a copper matrix as hardening particles [6,7]. The addition of certain secondary elements may increase the driving force for precipitation promoting the discontinuous precipitation (DP) [8][9][10][11]. This cellular DP in Cu-Ni-Si alloys tends to markedly decrease the mechanical properties, including hardness and strength [12][13][14].…”