Influence of tool rotational speed on mechanical and corrosion behaviour of friction stir processed AZ31/Al_(2)O_(3)nanocomposite

Nano-sized reinforcements improved the mechanical characteristics efficiently by promoting more implicit particle hardening mechanisms compared to micron-sized reinforcements.Nano-sized particles lessen the critical particle solidification velocity for swamp and thus offers better dispersal.In the present investigation,the friction stir processing(FSP)is utilized to produce AZ31/Al_(2)O_(3)nanocomposites at various tool rotation speeds(i.e.,900,1200,and 1500 rpm)with an optimized 1.5%volume alumina(Al_(2)O_(3))reinforcement ratio.The mechanical and corrosion behavior of AZ31/Al_(2)O_(3)-developed nanocomposites was investigated and compared with that of the AZ31 base alloy.The AZ31 alloy experienced a comprehensive dynamic recrystallization during FSP,causing substantial grain refinement.Grain-size strengthening is the primary factor contributed to the enhancement in the strength of the fabricated nanocomposite.Tensile strength and yield strength values were lower than those for the base metal matrix,although an upward trend in both values has been observed with an increase in tool rotation speed.An 19.72%increase in hardness along with superior corrosion resistance was achieved compared to the base alloy at a tool rotational speed of 1500 rpm.The corrosion currents(Jcorr)of all samples dropped with increase in the rotational speed,in contrast to the corrosion potentials(Ecorr),which increased.The values of Jcorr of AZ31/Al_(2)O_(3)were 42.3%,56.8%,and 65.5%lower than those of AZ31 alloy at the chosen rotating speeds of 900,1200,and 1500 rpm,respectively.The corrosion behavior of friction stir processed nanocomposites have been addressed in this manuscript which has not been given sufficient attention in the existing literature.Further,this work offers an effective choice for the quality assurance of the FSP process of AZ31/Al_(2)O_(3)nanocomposites.The obtained results are relevant to the development of lightweight automobile and aerospace structures and components.

Photon interaction with semiconductor and scintillation detectors

Mass attenuation coefficients,effective atomic numbers,and electron densities for semiconductor and scintillation detectors have been calculated in the photon energy range 1 keV-100 GeV.These interaction parameters have been found to vary with detector composition and the photon energy.The variation in the parameters with energy is shown graphically for all the partial photon interaction processes.The effective atomic numbers of the detector were compared with the ZXCOM program,and the results were found to be comparable.Efficiencies of semiconductor and scintillation detectors are presented in terms of effective atomic numbers.The study should be useful for comparing the detector performance in terms of gamma spectroscopy,radiation sensitivity,radiation measurement,and radiation damage.The results of the present investigation should stimulate research work for gamma spectroscopy and radiation measuring materials.

Shielding effectiveness of boron-containing ores in Liaoning province of China against gamma rays and thermal neutrons

In this study, the mass attenuation coefficient of boron-containing ores in the Liaoning province of China was calculated using Win XCOM software to investigate the shielding effectiveness of these ores against gamma rays. The mass attenuation coefficients were also calculated using MCNP-4 B code and compared with Win XCOM results; consequently, a good consistency between the results of Win XCOM and MCNP-4 B was observed. Furthermore, the G-P fitting method was used to evaluate the values of exposure buildup factor(EBF) in the energy range of 0.015–15 Me V up to 40 mean free paths. Among the selected ores, boron-bearing iron concentrate ore(M3)was determined to be the best gamma ray shielding ore owing to its higher values of mass attenuation coefficient and equivalent atomic number and lower value of EBF.Moreover, American Evaluated Nuclear Data File(ENDF/B-VII) was used to analyze the shielding effectivenessagainst thermal neutrons. It was determined that Szaibelyite(M2) is the best thermal neutron shielding material.This study would be useful for demonstrating the potential of boron-containing ores for applications in the field of nuclear engineering and technology.

Gamma-ray and neutron shielding efficiency of Pb-free gadolinium-based glasses

The radiation shielding efficiency of material depends upon photon attenuation, exposure buildup factors and neutron removal capacity. A newly developed Pb-free gadolinium-based glasses in compositions(80-x) B_2O_3-10 Si O_2-10 Ca O-x Gd_2O_3(where x = 15, 20, 25, 30 and35 mol%) had completely been investigated for their shielding efficiency with Geant4 simulation for mass attenuation coefficients and neutron total macroscopic cross section and by calculating exposure buildup factors.The exposure buildup factors for photon energy from 0.015 to 15 Me V had been calculated up to 40 mean free paths using five factors geometric progression method. The mass attenuation coefficients of the Pb-free glasses were simulated for energies from 223 to 2614 ke V and compared with the possible available experimental results. The neutron shielding efficiency of these glasses was discussed by calculating neutron total macroscopic cross section for energies from 1 e V to 14.1 Me V. Present investigations are found to be very useful for applications in nuclear engineering.

水库洪水波传播的波速分析

本文对水库洪水波传播的波速进行了研究。结果表明:运动波波速代表洪峰处的传播速度,而惯性波波速则代表波锋处的传播速度;天然河道或水库河流区观测的洪峰波速是运动波波速,而在水库平水区通过闸门启闭观测到的波速则是惯性波波锋处的传播速度。

绿豆裂叶的遗传

大多数绿豆(Vigna radiata(Linn.)Wilczek)的品种和种质系具有卵圆形小叶的三出复叶,但有些品系象‘K141’、‘GC1’和‘LM293’却有深裂片的小叶。Singh(1980)报道过裂叶对正常卵圆形叶呈单基因显性。我们试验了具有不同叶型品系的其中6个杂交组合,观察到裂叶的遗传涉及到重复基因。

Wave Interaction and Resonance in a Non-Ideal Gas

The method of multiple time scales is used to obtain the asymptotic solutions to the planar and non-planar flows into a non-ideal gas.The transport equations for the amplitudes of resonantly interacting high frequency waves are also found.Furthermore,the evolutionary behavior of non-resonant wave modes culminating into shock waves is studied.

印度汉干河的污染研究及污染的生物评价

对于印度汉干河的污染研究,其重点是放在对水质的生物评价上。本研究襄括精密的分析;在印度汉干河环境条件中,对欧洲多种用于水污染的生物监测方法进行了尝试;研究中将此河分成几个不同的污染带。将生物资料与化学资料联系起来,讨论了在印度环境中欧洲污水生物系统的实际内含物。同时还讨论了在河流水质评价中,水生大型无脊椎动物的重要性。