H.Wang
,
S.L.Ogin
,
A.M.Thorne
,
G.T.Reed
材料科学技术（英文）
Polarimetric optical fibre sensors have been embedded within the 0℃ ply and close to the 0/90 interface of transparent cross-ply GFRP coupons. The laminate ply cracks may initiate and propagate across the coupon when the coupons were subjected to an increasing quasi-static load in a servo-hydraulic testing machine. Crack accumulation have been monitored using a long gauge-length extensometer. The response of the strain signal, the optical signal and the load signal to cracks at different positions in the coupon in relation to the extensometer and optical sensor positions have been acquired and compared by means of video images of the crack growth. The relationship between crack growth and sensor response was demonstrated. The displacement induced by a new transverse crack has been predicted and compared with experimental data.
关键词:
Matrix cracking
,
cracking
,
Polarimetric
,
sensor
,
Four
韩娇
,
李莉
,
杨金文
,
周旺松
,
俞峰
,
曹文全
钢铁研究学报
doi:10.13228/j.boyuan.issn1001-0963.20140400
利用Gleeble-3800热模拟变形试验机,对高温轴承钢G80T的动态再结晶行为及相关力学性能进行了研究.通过对该钢在1050℃下以10s-1的变形速率进行0％～70％的不同形变量的单道次压缩,研究了不同形变量下热变形钢的微观组织结构及硬度.结果表明:当形变量在20％时,无动态再结晶发生;当形变量达到40％时,热变形组织出现了部分的再结晶晶粒;随着形变量的进一步加大,再结晶晶粒数目增多,形变量达到60％后,形变组织形成了平均晶粒尺寸为2.8μm的完全再结晶组织.同时由于形变和晶粒尺寸大幅度细化,钢中的碳化物也随着形变量的增加而逐步减少.通过对压缩应力-应变曲线软化行为的分析,认为该钢的再结晶属于动态再结晶;在1050℃进行60％的形变可以实现该钢的完全动态再结晶,将平均晶粒尺寸从原始的22μm细化到2.8μm,同时将钢的硬度从820HV提高到895HV.研究结果表明,动态再结晶是细化高温轴承钢G80T晶粒尺寸和提高性能的一种有效措施.
关键词:
高温轴承钢
,
热压缩
,
动态再结晶
,
晶粒细化
,
显微硬度
尤力
,
宋西平
机械工程材料
对高温运行78000h后的T91／G102异种钢焊接接头向火侧进行了常温拉伸、冲击、硬度和高温持久试验，并对其进行了寿命估算。结果表明：长时运行后，接头两侧母材常温抗拉强度仍满足要求，但焊接接头的常温抗拉强度已低于标准值；两侧母材的冲击韧性仍较高，但G102钢侧及T91钢侧熔合线处的冲击功最低；T91钢母材的显微硬度同运行前的基本相当，而T9l钢侧热影响区、焊缝、G102钢侧热影响区以及G102钢侧母材的显微硬度均明显降低；G102钢热影响区的高温蠕变性能最差；焊接接头向火侧的剩余寿命为27601h，但焊缝、热影响区性能的劣化将大大降低其安全运行可靠性；G102钢侧热影响区析出的碳化物与两侧母材析出的明显不同。
关键词:
异种钢
,
焊接接头
,
性能
,
剩余寿命
Communications in Theoretical Physics
By using the wavefunctions obtained from diagonalizing the complete d(3) energy matrix at normal and various pressures, the g factor of the ground state of SrTiO3:Cr3+ and its pressure-induced shift have been microscopically calculated. Only by taking the local strains around Cr3+ in SrTiO3:Cr3+ (which are about twice the bulk ones) and corresponding P-chi dependence, can we obtain a good agreement between the calculated result of pressure-induced shift of ground-state g factor and the experimental one. The physical origins of this pressure-induced shift have been explained. It is found that the change of Dq(-1) with pressure makes main contribution to the pressure-induced shift of ground-state g factor of SrTiO3:Cr3+. By using the wavefunctions obtained from diagonalizing the complete d3 energy matrix at normal pressure, the relevant matrix elements and accordingly strain-induced splittings of t(2)(3) E-2 and t(2)(3) (4)A(2) of SrTiO3:Cr3+ have been calculated. The important results of Y-c, Z(c), P-c and Q(c) have also been evaluated. It is the admixtures of basic wavefunctions resulted from the spin-orbit interaction and/or Coulomb interaction and/or Kramers degeneracy that make the strain-induced splittings of the levels nonzero. It is found that there are nonvanishing matrix elements of operators T2 xi, T2 eta and T2 zeta between wavefunctions with positive M-s and those with negative M-s', which have important effects on the strain-induced splittings of the levels.
关键词:
crystal fields;energy spectrum;g factors;high-pressure effect;strain-induced splitting;theoretical calculations;ruby;crystal
Physica B-Condensed Matter
The temperature dependence of EPR g factor for MgO:V2+ crystal has been studied theoretically by considering both the static contribution due to the thermal expansion of crystal and the vibrational contributions due to the electron-phonon interaction of the acoustic and optical branches. The static contribution is calculated from the high-order perturbation formula of g factor and the thermal expansion coefficients alpha(T) at various temperatures. The vibrational contribution of acoustic phonons is obtained by using a Debye model for the lattice vibrations and that of optical phonons is calculated by use of a single frequency model. The calculated results show that for the g factor at various temperatures, the static contribution is dominant, but for the temperature dependence of g factor, i.e., (dg/dT)(p) or Delta g(T) = g(T) - g(0), the vibrational contributions from the acoustic and optical phonons are comparable with the static contribution due to thermal expansion. It appears that a reasonable theoretical explanation for the temperature dependence of g factor should take all of these contributions into account.
关键词:
impurities
Chinese Physics Letters
Al(85)Ni(5)Y(8)Co(2) and Al(85)Ni(5)Y(6)Co(2)Fe(2) metallic glasses are fabricated by melt spinning. A kink or a small exothermic peak is observed for both the samples isothermally annealed at sub-glass transition temperatures. Temperature modulated differential scanning calorimetry (TMDSC) data disapprove amorphous phase separation. The activation energies derived from Kissinger plots of the exothermic process on DSC curve around glass transition temperature are consistent with those of beta-relaxation of metallic glasses.
关键词:
phase-separation;nanocrystalline alloys;crystallization;transition;behavior
