J Mater Sci Technol ›› 2004, Vol. 20 ›› Issue (01): 99-102.

• Research Articles • Previous Articles     Next Articles

Microstructural Changes of Cu-Ni-Si Alloy during Aging

Qiming DONG, Dongmei ZHAO, Ping LIU, Buxi KANG, Jinliang HUANG   

  1. Department of Materials Engineering, Henan University of Science and Technology, Luoyang 471003, China
  • Received:1900-01-01 Revised:1900-01-01 Online:2004-01-28 Published:2009-10-10
  • Contact: Ping LIU

Abstract: Age hardening in Cu-3.2Ni-0.75Si(wt pct) and Cu-1.0Ni-0.25Si (wt pct) alloys from 723 to 823 K is studied. After an incubation period strengthening appears which is due to precipitates in the Cu-1.0Ni-0.25Si (wt pct) alloy. On other hand an immediate increase of the yield strength characterizes the aging of the alloy. This is followed by the regions of constant yield strength and further by a peak. The microstructure of the alloy was studied by, means of transmission electron microscope (TEM) and X-ray diffraction (XRD). Spinodal decomposition takes place followed by nucleation of the ordering coherent (Cu,Ni)3Si particles, further precipitation annealing coherent δ-Ni2Si nucleated within the (Cu,Ni)3Si particle. Any change of the yield strength can be described by an adequate change of the structure in the sample. The nature of the aging curves with a "plateau" is discussed. The formulas of Ashby and Labusch can be used to explain the precipitation.

Key words: Copper alloy, Transformation, Ageing, Spinodal decomposition, Ordering, Yield strength