In situ observation of the growth process of bainitic plate in βbrass by means of high-temper- ature TEM is conducted.The lengthening and thickening kinetics of bainitic plate is analysed with Trivedi's model and...In situ observation of the growth process of bainitic plate in βbrass by means of high-temper- ature TEM is conducted.The lengthening and thickening kinetics of bainitic plate is analysed with Trivedi's model and Zener-Hillert's model,respectively.It is found that the stacking fault substructure exists just in the growth tip of fresh bainitie plate and so does the shear stress in the matrix around the tip.The measured lengthening rate of bainitic plate is not con- sistent with Trivedi's model.The thiekening process is only macroscopieally controlled by vol- ume diffusion but its nature is a shear process.展开更多
The AuSn20/Ni joints were prepared by the reflow soldering technology and then annealed at solid-state temperature to form diffusion couples.The interfacial reactions and the growth kinetics of the intermetallic compo...The AuSn20/Ni joints were prepared by the reflow soldering technology and then annealed at solid-state temperature to form diffusion couples.The interfacial reactions and the growth kinetics of the intermetallic compounds(IMC)at the AuSn20/Ni soldering interface were investigated by scanning electron microscopy(SEM)and electron probe microanalysis(EPMA).The results show that,the(Ni,Au)3Sn2phases are formed at the AuSn20/Ni interface after soldering at583K.The thickness l of the IMC layer monotonically increases with increasing annealing time t according to the relationship l=k(t/t0)n,where the exponent n is0.527,0.476and0.471for393,433and473K annealing,respectively.This indicates that the volume diffusion contributes to the growth of the IMC layer at the AuSn20/Ni interface at solid-sate temperature.The pre-exponential factor K0=1.23×10?7m2/s and the activation enthalpy QK=81.8kJ/mol are obtained from the results of the parabolic coefficient K by a least-squares method.展开更多
Stainless steel samples were made by Powder injection Molding (PIM) process with-400 mesh powder in order to investigate the sintering mechanism in this system and develop the PIM of stainless steels. The process incl...Stainless steel samples were made by Powder injection Molding (PIM) process with-400 mesh powder in order to investigate the sintering mechanism in this system and develop the PIM of stainless steels. The process included mixing, injection molding, debin- ding and sintering. Neck growth model was used to analyze the sintering mechanism. The results show that lattice (volume) diffusion is the main mechanism in the sintering process, the products with higher density (>95%) and properties are obtained. At lower temperatures, grain boundary diffusion may play a role in the sintering densification.展开更多
文摘In situ observation of the growth process of bainitic plate in βbrass by means of high-temper- ature TEM is conducted.The lengthening and thickening kinetics of bainitic plate is analysed with Trivedi's model and Zener-Hillert's model,respectively.It is found that the stacking fault substructure exists just in the growth tip of fresh bainitie plate and so does the shear stress in the matrix around the tip.The measured lengthening rate of bainitic plate is not con- sistent with Trivedi's model.The thiekening process is only macroscopieally controlled by vol- ume diffusion but its nature is a shear process.
基金Project(JPPT-125-GH-039)supported by the Ministry of Science and Technology of ChinaProject(Z109021567)supported by Fundamental Research Funds for the Central Universities,China
文摘The AuSn20/Ni joints were prepared by the reflow soldering technology and then annealed at solid-state temperature to form diffusion couples.The interfacial reactions and the growth kinetics of the intermetallic compounds(IMC)at the AuSn20/Ni soldering interface were investigated by scanning electron microscopy(SEM)and electron probe microanalysis(EPMA).The results show that,the(Ni,Au)3Sn2phases are formed at the AuSn20/Ni interface after soldering at583K.The thickness l of the IMC layer monotonically increases with increasing annealing time t according to the relationship l=k(t/t0)n,where the exponent n is0.527,0.476and0.471for393,433and473K annealing,respectively.This indicates that the volume diffusion contributes to the growth of the IMC layer at the AuSn20/Ni interface at solid-sate temperature.The pre-exponential factor K0=1.23×10?7m2/s and the activation enthalpy QK=81.8kJ/mol are obtained from the results of the parabolic coefficient K by a least-squares method.
文摘Stainless steel samples were made by Powder injection Molding (PIM) process with-400 mesh powder in order to investigate the sintering mechanism in this system and develop the PIM of stainless steels. The process included mixing, injection molding, debin- ding and sintering. Neck growth model was used to analyze the sintering mechanism. The results show that lattice (volume) diffusion is the main mechanism in the sintering process, the products with higher density (>95%) and properties are obtained. At lower temperatures, grain boundary diffusion may play a role in the sintering densification.
