H.Z. Huang
,
X.Q. Wei
,
L. Zhou
,
null
,
null
金属学报(英文版)
The potential of using a hypoeutectic, instead of eutectic, Sn-Zn alloy as a lead-free solder has been discussed. The nonequilibrium melting behaviors of a series of Sn-Zn alloys were examined by differential thermal analysis. It was found that at a heating rate of 5℃ / min, Sn-6.5Zn exhibited no melting range. Dipping and spreading tests were carried out to characterize the wettability of Sn-Zn alloys on Cu. Both tests exhibited that Sn-6.5Zn has significantly better wettability on Cu than Sn-9Zn. The reaction layers formed during the spreading tests were examined. When the Zn concentration fell between 2.5wt%-9wt%, two reaction layers were formed at the interface, a thick and flat Cu5Zn8 adjacent to Cu and a thin and irregular Cu-Zn-Sn layer adjacent to the alloy. Only a Cu6Sn5 layer was formed when the Zn concentration decreased to 0.5wt%. The total thickness of the reaction layer(s) between the alloy and Cu was found to increase linearly with the Zn concentration.
关键词:
lead-free solder
,
Sn-Zn合金
,
润湿性
,
界面
,
金属间化
L. Zhou
,
X.Q. Wei
,
N.G. Zhou
金属学报(英文版)
Molecular dynamics simulations of high temperature annealing of copper bicrystals
have been carried out. The bicrystals have planar grain boundaries, and the gain
size varies in nano range. An EAM(Embedded Atom Method) potential of FS type is
used for calculating the interatomic forces. The results show that in nanocrystalline
copper, GB migration driven by inter-GB reaction can take place. A critical grain
size is identi¯ed, below which the inter-GB reaction becomes strong enough to trigger
GB motion, which accelerates rapidly and leads to annihilation of the grain bound-
aries. The critical size is found to be 16 atomic radii. A \through intermediate grain
mechanism" is identi¯ed for the nano-grain boundary motion observed, which is never
reported for GB migrations of conventional polycrystalline metals.
关键词:
grain boundary migration
,
null
,
null
