An in situ synchrotron X-ray diffraction study of precipitation kinetics in a severely deformed Cu–Ni–Si alloy

An X-ray absorption spectroscopy investigation of the local atomic structure in Cu–Ni–Si alloy after severe plastic deformation and ageing

“…Discs of the same alloy were processed via HPT under 6.0 GPa for 10 revolutions at room temperature. The detailed sample preparations and SPD processing and in situ ageing are reported elsewhere [6]. Samples after processing by ECAP and HPT were subject to in situ accumulated ageing up to 973 K. The analyzed samples will be named here after ECAP 8, ECAP 8 AGED, HPT 10 and HPT 10 AGED.…”

“…The results indicated that the deformation process has a major influence on both the nature and the sequence of the precipitation in the Cu-Ni-Si alloy [6]. An in situ ageing at 723 K of samples processed by ECAP led to the precipitation of δ-Ni 2 Si and β-Ni 5 Si 2 phases.…”

“…The precipitation behaviour in Cu-Ni-Si alloy during isothermal ageing after straining by ECAP and HPT was investigated in the previous work [6]. The results indicated that the deformation process has a major influence on both the nature and the sequence of the precipitation in the Cu-Ni-Si alloy [6].…”

Discontinuous precipitates in age-hardening CuNiSi alloys

“…The precipitating phase responsible for the age-hardening has been investigated by a number of researchers, especially regarding the early stages of aging [6][7][8][9][10][11][12][13][14][15]. To date, the age-hardening precipitates in the alloys have been widely accepted as being δ-Ni 2 Si intermetallics with an orthorhombic structure [6][7][8][9][10][11][12][13][14][15][16][17], although other types of precipitates, such as β-Ni 3 Si, (Cu,Ni) 3 Si, and other metastable phases, might coexist [8,[12][13][14][15].…”

“…To date, the age-hardening precipitates in the alloys have been widely accepted as being δ-Ni 2 Si intermetallics with an orthorhombic structure [6][7][8][9][10][11][12][13][14][15][16][17], although other types of precipitates, such as β-Ni 3 Si, (Cu,Ni) 3 Si, and other metastable phases, might coexist [8,[12][13][14][15]. In their most recent study, Hu et al investigated the subsequent age-hardening of δ-Ni 2 Si precipitates (i.e., continuous precipitates (CPs)) that form during isothermal aging, and explained their behavior using classical theories of phase transformation in association with energy calculations [14]; the CPs in Cu-2.6 Ni-1.6 Si-0.5 Cr (in at.%) alloys did not exhibit any changes in their δ-Ni 2 Si crystal structure, but underwent changes in their morphology and other crystallographic features.…”