Activation of hydrogen storage materials in the Li–Mg–N–H system: Effect on storage properties

We investigate the thermodynamics, kinetics, and capacity of the hydrogen storage reaction: Li₂Mg(NH)₂ + 2H₂  Mg(NH₂)₂ + 2LiH. Starting with LiNH₂ and MgH₂, two distinct procedures have been previously proposed for activating samples to induce the reversible storage reaction. We clarify here the impact of these two activation procedures on the resulting capacity for the Li–Mg–N–H reaction. Additionally, we measure the temperature-dependent kinetic absorption data for this hydrogen storage system. Finally, our experiments confirm the previously reported formation enthalpy (ΔH), hydrogen capacity, and pressure–composition–isotherm (PCI) data, and suggest that this system represents a kinetically (but not thermodynamically) limited system for vehicular on-board storage applications.     

机械振动对Sn-Sb合金β相的影响

初步探讨了机械振动对Sn-Sb合金β相在基体中分布的影响,重点讨论了在不同振击力作用下对Sn-Sb11合金中β相(SnSb)偏析和细化的影响效果.试验表明,在不同振击力作用下,合金晶粒以及组织明显得到改善,而且随着振击力的增大,组织均匀化程度的改善效果呈明显上升趋势.分析结果表明,这是由于强烈的振动对金属液体的搅拌以及促使合金液晶粒(或晶团)的游离作用的缘故.     

压铸条件和淬火时效对GD—AlSi9Cu3合金力学性能的影响

通过改变压铸工艺参数和淬火时效，测定在静态载荷和动态循环载荷下ＧＤＡｌＳｉ９Ｃｕ３合金的力学性能和断裂力学性能，试验所获得的数据可用来估算压铸件的失效风险率     

Role of deposition parameters on microstructure and mechanical properties of chromium oxide coatings

Chromium oxide coatings were deposited by reactive magnetron sputtering on high speed steel (HSS) substrate under various oxygen flow rates and radio frequency (RF) powers. The effect of deposition conditions on the microstructure, hardness and critical load of chromium oxide coating failure was studied. The results indicated that a crystalline chromium oxide coating formed at a high oxygen flow rate and a low RF power exhibited a higher hardness and a lower critical load as compared to a chromium oxide coating with an amorphous microstructure.     

压力机气垫故障分析

介绍分析了机械压力机气垫通常出现的故障现象，以及应采取的排障措施。     

稀土元素Ce对纯铜导电性及力学性能的影响

在纯铜中加入稀土元素Ce,研究不同含量Ce及不同保温时间对纯铜的导电性、抗拉强度、硬度、耐磨性等的影响.研究发现在纯铜中加入Ce起到净化、去杂质的作用,改善纯铜的导电性;也可使晶粒细化,改善纯铜的抗拉强度及其它力学性能.且熔炼时加入稀土后的保温时间要适当.在试验的条件下保温时间以30 min为宜,稀土Ce的最佳加入量w为0.02%.     

Effects of annealing at high pressure on structure and mechanical properties of Al87Ni7Gd6 metallic glass

The effects of annealing and annealing with a superimposed pressure of 940 MPa on the primary crystallization behaviour of α-Al and the resulting micro-hardness have been studied for as-quenched Al₈₇Ni₇Gd₆ metallic glass. Isothermal annealing experiments were conducted for 30 min at 188 °C, 191 °C, and 205 °C in silicone oil maintained either at atmospheric pressure (i.e. 0.1 MPa) or at 940 MPa. XRD analyses detected the evolution of structure with annealing at 0.1 MPa, while specimens annealed with 940 MPa pressure exhibited sharper diffraction peaks than those annealed at 0.1 MPa. DSC measurements were conducted on the as-received amorphous ribbons as well as ribbons annealed at different temperatures at either 0.1. MPa or with 940 MPa superimposed pressure. Specimens annealed with 940 MPa pressure exhibited higher onset temperatures (i.e. T_x1) and temperatures for the first exothermic peak (i.e. T_p1) for primary crystallization. TEM measurements revealed an increase in the volume fraction of α-Al with increases in annealing temperature, while micro-hardness measurements revealed an increase in hardness with increasing amounts of α-Al. Specimens annealed with 940 MPa pressure exhibited further increases in both the volume fraction of α-Al and resulting micro-hardness.     

非调质钢的合金设计与热加工工艺及性能

论述了非调质钢的性能特点，分析了V、Nb、Ti、Mn、Cr、Si等常用合金元素对非调质钢组织和力学性能的影响，并对热加工工艺、热处理等因素个性能的影响作了分析和讨论。     

利用"正火液"作为高铬铸铁磨球淬火介质的生产实践

高铬铸铁件在没有添加贵重元素的条件下,利用"正火液"配入适量的水作为淬火介质进行了试验和生产.实践证明,产品在热处理淬火时从未发生炸裂现象,同时完全达到了要求的力学性能指标.生产的锤头其使用寿命为高锰钢的6～8倍,为低铬白口铸铁的4～6倍.     

Synthesis and characterization of mechanical-alloyed Ti–xMg alloys

The synthesis and characterization of Ti–xMg (x=4, 9, 12, 15, 21, 24 at%) alloys using mechanical alloying was investigated. A nanometer-sized Ti–24Mg alloy was produced. During mechanical alloying, the height of the XRD peaks of the Mg in the Ti–9Mg alloy decreased, and then disappeared, whereas the Ti XRD peaks broadened, and the grain size decreased with increasing milling time. The Mg firstly dissolved in the grain boundaries of the Ti, and then diffused into the Ti grain interiors. The grain boundaries played an important role in enhancing the solid solubility of Mg in Ti. With increasing Mg content the volume fraction of grain boundaries increased, and a decrease in grain size occurred after mechanical alloying for 48 h.