摘要:

A model of the fragmentation process is developed, based on the theory of linear elastic fracture mechanics, which predicts the average fragment size as a function of strain rate and material properties. This approach permits a unification of previous results, yielding Griffith’s solution in the low‐strain‐rate limit and Grady’s solution at high strain rates.

ISSN:0021-8979    

DOI:10.1063/1.337373

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Effects of the heat treatment condition on the high‐field superconducting performances of the surface diffusion processed V3Ga have been investigated.Icat fields nearHc2depends mainly on the layer thickness andHc2of V3Ga. The two‐stage reaction process, which consists of the first reaction at the higher temperature to form a thick enough V3Ga layer and the subsequent second reaction at the lower temperature to achieve high values ofTcandHc2, has been found to improve appreciably theIcof SDP V3Ga in high magnetic fields. OverallJc(including copper stabilizer) of about 2.0×104A/cm2at 19 T has been obtained for a ∼100‐m‐long V3Ga tape.

ISSN:0021-8979    

DOI:10.1063/1.337374

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

An analysis of the two‐electron satellites of the dominant donor‐bound exciton line in photoluminescence of ZnSe layers grown on (100)GaAs by molecular‐beam epitaxy indicates that the donor impurity is likely gallium. Strain in the ZnSe epitaxial layers as evidenced by a shift in the positions of the excitonic lines is shown to depend on the growth temperature and is a minimum at about 365 °C. At growth temperatures different from 365 °C theIGa20line is observed shifted by as much as 3 meV. The relatively small shift of ∼0.4 meV in our layers grown at 365 °C may be due to a strain‐relief inelastic process; it is suggested that one possibility might be the formation of a misfit dislocation network at the interface.

ISSN:0021-8979    

DOI:10.1063/1.337375

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

It is shown how the transition from a positive to a negative voltage–current characteristic can be accomplished in a pulsed, low‐pressure, high‐current hydrogen discharge. This transition is observed to be related to the onset of instability in the discharge. The instability is characterized by the formation of non‐steady‐state, high‐energy, high‐mobility electrons similar to those occurring in arcs or sparks.

ISSN:0021-8979    

DOI:10.1063/1.337376

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

The activation energy for electromigration failure was determined for Al‐4% Cu conductor stripes covered with polyimide. The activation energy was measured to be 0.88 eV, which is substantially higher than that measured previously for similar systems under glass. The difference in the activation energies is attributed to the possible presence of hydrogen in the Al–Cu grain boundaries.

ISSN:0021-8979    

DOI:10.1063/1.337325

出版商:AIP    

年代:1986

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.337803

出版商:AIP    

年代:1986

数据来源: AIP