Cu–Ni–P alloys combine excellent mechanical properties and electrical conductivity are considered the ideal materials for next-generation electronic components. In this study, we have identified a new mechanism for the crystallographic transformation of the precipitated in a Cu-0.96Ni-0.22P alloy, which may unravel the long-standing misunderstandings of the precipitation behavior in Cu–Ni–P alloys. The crystallographic and morphological evolution of two types of Ni2P precipitates found in this study was investigated in detail via transmission electron microscopy (TEM), aberration-corrected TEM (ACTEM), and atom probe tomography (APT), etc. The increase in aging temperature promoted the evolution of Ni2P phase from spherical to the disk-shaped, which can be regarded as a 5.6° rotation along the <InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="12598_2025_3488_Article_IEq1.gif" Format="GIF" Height="23" Rendition="HTML" Resolution="72" Type="Linedraw" Width="67" /> </InlineMediaObject> <EquationSource Format="TEX">${[40\overline{4 }0]}_{\text{Ni}_2\text{P}}$</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mrow> <mo stretchy="false">[</mo> <mn>40</mn> <mover> <mn>4</mn> <mo>¯</mo> </mover> <mn>0</mn> <mo stretchy="false">]</mo> </mrow> <mrow> <msub> <mtext>Ni</mtext> <mn>2</mn> </msub> <mtext>P</mtext> </mrow> </msub> </math></EquationSource> </InlineEquation> axis according to three-dimensional reconstruction results. The high-index <InlineEquation ID="IEq2"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="12598_2025_3488_Article_IEq2.gif" Format="GIF" Height="23" Rendition="HTML" Resolution="72" Type="Linedraw" Width="71" /> </InlineMediaObject> <EquationSource Format="TEX">${(12\overline{3 }\overline{2 })}_{\text{Ni}_2\text{P}}$</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mrow> <mo stretchy="false">(</mo> <mn>12</mn> <mover> <mn>3</mn> <mo>¯</mo> </mover> <mover> <mn>2</mn> <mo>¯</mo> </mover> <mo stretchy="false">)</mo> </mrow> <mrow> <msub> <mtext>Ni</mtext> <mn>2</mn> </msub> <mtext>P</mtext> </mrow> </msub> </math></EquationSource> </InlineEquation> face demonstrates a lower interfacial misfit after the transformation, which promotes the growth of both the <InlineEquation ID="IEq3"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="12598_2025_3488_Article_IEq2.gif" Format="GIF" Height="23" Rendition="HTML" Resolution="72" Type="Linedraw" Width="71" /> </InlineMediaObject> <EquationSource Format="TEX">${(12\overline{3 }\overline{2 })}_{\text{Ni}_2\text{P}}$</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mrow> <mo stretchy="false">(</mo> <mn>12</mn> <mover> <mn>3</mn> <mo>¯</mo> </mover> <mover> <mn>2</mn> <mo>¯</mo> </mover> <mo stretchy="false">)</mo> </mrow> <mrow> <msub> <mtext>Ni</mtext> <mn>2</mn> </msub> <mtext>P</mtext> </mrow> </msub> </math></EquationSource> </InlineEquation> and <InlineEquation ID="IEq4"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="12598_2025_3488_Article_IEq4.gif" Format="GIF" Height="23" Rendition="HTML" Resolution="72" Type="Linedraw" Width="71" /> </InlineMediaObject> <EquationSource Format="TEX">${(40\overline{4 }0)}_{\text{Ni}_2\text{P}}$</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mrow> <mo stretchy="false">(</mo> <mn>40</mn> <mover> <mn>4</mn> <mo>¯</mo> </mover> <mn>0</mn> <mo stretchy="false">)</mo> </mrow> <mrow> <msub> <mtext>Ni</mtext> <mn>2</mn> </msub> <mtext>P</mtext> </mrow> </msub> </math></EquationSource> </InlineEquation> faces, ultimately forming a disk-shaped phase. The gradual replacement of Cu atoms in the low-Ni transition layer with Ni atoms and (Ni, Cu)2P layer is formed, which accelerates the transformation of the disk-shaped Ni2P phase. This work is essential for promoting the microstructural design of Cu–Ni–P systems and provides new insights into the properties control in Cu–Ni–P alloys. Graphical abstract

New insights into the precipitation behavior of Cu–Ni–P alloy driven by crystallographic transformation of nano-precipitates with different heat treatments

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发表日期：

2025年8月7日

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Yun-Qing Zhu,
Li-Jun Peng,
Xu-Jun Mi,
Guo-Jie Huang,
Zhen Yang,
Shu-Hui Huang,
Hong-Tao Zhang,
Ji-Bao Li,
Jun-Sheng Wu,
Hao-Feng Xie

摘要

Cu–Ni–P alloys combine excellent mechanical properties and electrical conductivity are considered the ideal materials for next-generation electronic components. In this study, we have identified a new mechanism for the crystallographic transformation of the precipitated in a Cu-0.96Ni-0.22P alloy, which may unravel the long-standing misunderstandings of the precipitation behavior in Cu–Ni–P alloys. The crystallographic and morphological evolution of two types of Ni₂P precipitates found in this study was investigated in detail via transmission electron microscopy (TEM), aberration-corrected TEM (ACTEM), and atom probe tomography (APT), etc. The increase in aging temperature promoted the evolution of Ni₂P phase from spherical to the disk-shaped, which can be regarded as a 5.6° rotation along the ${[40\overline{4 }0]}_{\text{Ni}_2\text{P}}$ ${[40 \bar{4} 0]}_{{Ni}_{2} P}$ axis according to three-dimensional reconstruction results. The high-index ${(12\overline{3 }\overline{2 })}_{\text{Ni}_2\text{P}}$ ${(12 \bar{3} \bar{2})}_{{Ni}_{2} P}$ face demonstrates a lower interfacial misfit after the transformation, which promotes the growth of both the ${(12\overline{3 }\overline{2 })}_{\text{Ni}_2\text{P}}$ ${(12 \bar{3} \bar{2})}_{{Ni}_{2} P}$ and ${(40\overline{4 }0)}_{\text{Ni}_2\text{P}}$ ${(40 \bar{4} 0)}_{{Ni}_{2} P}$ faces, ultimately forming a disk-shaped phase. The gradual replacement of Cu atoms in the low-Ni transition layer with Ni atoms and (Ni, Cu)₂P layer is formed, which accelerates the transformation of the disk-shaped Ni₂P phase. This work is essential for promoting the microstructural design of Cu–Ni–P systems and provides new insights into the properties control in Cu–Ni–P alloys.

Graphical abstract