摘要:

As a result of fast neutron bombardment, monoclinic ZrO2is transformed into the cubic phase normally stable only above 1900°C. It is suggested that the unique temperature‐structure behavior in the zirconia system lends itself to this transition in a manner whereby two possible mechanisms may be operative. Stresses acting about trapped interstitial atoms and thermal spike effects are presented as the possible mechanisms.

ISSN:0021-8979    

DOI:10.1063/1.1722448

出版商:AIP    

年代:1956

数据来源: AIP

摘要:

There have been several investigations of the electrical breakdown strength of hydrocarbon liquids in a high state of purity in which attempts have been made to correlate the strength with density or chain length. A simple relationship between these quantities did not exist when branched‐chain isomers of then‐paraffins were included. The present paper develops the theory of breakdown outlined by the author in a previous publication in which molecular vibrations in these liquids can provide an energy barrier to ionization by electrons and final breakdown. It is suggested that three major processes occur, namely, electron emission from the cathode, energy loss to molecular vibrations, and ionization of the liquid. The instability which marks breakdown is then induced by positive ions which result from ionization. Provided a suitable test procedure is employed it is possible to compare the energy‐loss mechanism in the various liquids by comparing their electric strengths. The nature of the molecular vibrations is discussed, and it is suggested that the infrared frequencies of the CH3, CH2, and CH groups undergoing bond stretching are excited by the electron motion. Such a frequency, characteristic of the carbon‐hydrogen bond would be common to all hydrocarbon liquids. Collision cross sections for these groups can then be assigned and a breakdown criterion set up which is analogous to that proposed by von Hippel for condensed phases. The general correctness of this theory is illustrated by reference to the measurements of Crowe, Sharbaugh, and Bragg and to new measurements obtained by the author. It is found to be possible to correlate not only the electric strength of straight‐chain hydrocarbons but branched‐chain isomers as well. Finally it is suggested that the current pulses frequently observed in conduction measurements inn‐hexane are possibly associated with bond deformation vibrations.

ISSN:0021-8979    

DOI:10.1063/1.1722449

出版商:AIP    

年代:1956

数据来源: AIP

摘要:

By measurement of the specific heat, temperature coefficient of expansion, Young's modulus and yield point in Cu3Au alloys, it has been established that this alloy undergoes a phase transition between 550° and 600°C and possibly another one near 850°C. The temperature of the 550–600°C transition decreases sharply as the composition of the alloy deviates from Cu3Au.

ISSN:0021-8979    

DOI:10.1063/1.1722450

出版商:AIP    

年代:1956

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.1722452

出版商:AIP    

年代:1956

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.1722453

出版商:AIP    

年代:1956

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.1722454

出版商:AIP    

年代:1956

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.1722457

出版商:AIP    

年代:1956

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.1722458

出版商:AIP    

年代:1956

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.1722459

出版商:AIP    

年代:1956

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.1722461

出版商:AIP    

年代:1956

数据来源: AIP