Effect of pulsed photon irradiation on the formation of a nanocrystalline structure in Fe-Pb-Nb amorphous alloys

X-ray diffraction, transmission electron microscopy, and microhardness and internal friction measurements are used to study the formation of a nanocrystalline structure in Fe-Pb-Nb amorphous alloys subjected to pulsed photon irradiation. The threshold light energies that are incident on a sample and cause nanocrystallization and hardening of amorphous alloys are found, and a model of crystal phase nucleation in amorphous alloys is developed.     

等离子喷涂钼基非晶纳米晶复合涂层的组织和电化学特性

用Mo基合金粉末(含Si,B,Cr,W,Mo,Ni等)作为喷涂材料,利用大气等离子喷涂(APS)技术,在0Cr13Ni5Mo不锈钢基体上制备了钼基非晶纳米晶复合涂层.利用XRD观察了涂层的晶型结构,扫描电镜(SEM)观察涂层的组织形貌,恒电位扫描仪对涂层的电化学特性进行了测试,显微硬度仪测量涂层的显微硬度.实验结果表明,利用等离子喷涂工艺可以制备高硬度的Mo基非晶纳米晶复合涂层,这种涂层结构均匀致密,其显微硬度最高达到1426.9HV.孔隙率约为5.5%.非晶纳米晶复合涂层在3.5%NaCl溶液中存在钝化现象,自腐蚀电流为6.459μA·cm^-2,腐蚀速度0.869mm·a^-1.     

Effect of the state of a melt on the glass-forming ability,structure, and properties of a melt-quenched bulk amorphous nickel-based alloy

The glass-forming ability, viscosity, phase composition, and microhardness of a melt-quenched Ni_64.4Fe₄Cr_4.9Mn₂B_16.2C_0.5Si₈ bulk amorphous alloy quenched from various melt temperatures at near-critical rates are studied. The melt-quenching temperature ensuring the maximum glass-forming ability and microhardness (HV= 13 GPa) of the alloy is found to be 1200–1230°C. The melt viscosity is shown to behave anomalously near the solidification temperature, and the related factors favoring this anomalous behavior are detected.     

Mechanism of the formation of an amorphous (for X-ray diffraction) structure in electrodeposited Co-W alloy films

The structure formation in electrodeposited Co-W alloy films is studied. As the tungsten content in the films increases to 20 at %, a phase transition from a polycrystalline into an amorphous (as determined by X-ray diffraction) state takes place. A mechanism is proposed for the formation of the amorphous structure in the films.     

Effect of electrolysis conditions on the formation,structure, and magnetic properties of a finely divided iron-cobalt alloy

Conclusions Changing the Fe²⁺Co²⁺ ratio in the electrolyte strongly affects the composition of the alloy but not its current efficiency; the current efficiency falls only at iron-to-cobalt ratios in excess of 11. At a high cobalt ion concentration in the electrolyte both the current efficiency and the cobalt content of the alloy cease to vary proportionally to the ion concentration. An x-ray diffraction investigation has established that increasing the cobalt ion concentration in the electrolyte decreases the size of iron-cobalt alloy blocks, which manifests itself in the ratio range Fe²⁺Co²⁺=0.6. When this ratio is exceeded, the -phase of the iron-cobalt alloy becomes amorphous, but on the whole the particles of the deposit retain a crystalline structure owing to the presence of an independent crystalline cobalt phase. At high cobalt ion concentrations in the electrolyte the particles forming by electrolysis constitute a pseudoalloy consisting of the -phase of the cobalt alloy and the and -modifications of metallic cobalt. Lowering the Fe²⁺ Co²⁺ ratio brings about a steady decrease in the crystal lattice constant. Magnetic measurements have revealed the existence of maximum values of coercive force and magnetic induction in a range of Fe²⁺ Co²⁺ ratios close to unity.Translated from Poroshkovaya Metallurgiya, No. 9 (225), pp. 1–5, September, 1981.     

Effect of electrolysis conditions on the formation,structure, and magnetic properties of a finely divided iron-cobalt alloy

Conclusions An investigation was carried out into the effect of electrolyte concentration and current density on current efficiency in the electrodeposition of Fe, Co, and Fe-Co alloy powders. It was established that raising the electrolyte concentration from 6.65 to 26.62 g/liter of Fe²⁺ + Co²⁺ increases current efficiency, whose maximum value is about 90%. The highest current efficiency is attained at i_c of 20–30 A/dm². Changing the electrolyte concentration and current density does not significantly affect the composition of alloy deposits. At an iron-to-cobalt ion content ratio in the electrolyte of 11 the rate of discharge of Fe²⁺ during alloy formation in the twolayer bath is greater than that of Co²⁺. X-ray structural analysis revealed that the greatest changes in the internal structure of a very finely divided iron-cobalt alloy take place at low electrolyte concentrations. That raising the electrolyte concentration facilitates alloy formation is confirmed by a decrease in the degree of defectiveness of the particles and a stabilization of the crystal lattice parameter of the alloy; i_c does not have such an effect on the structure of the alloy. Magnetometric measurements demonstrated that the coercive force of alloy powders is greater at higher densities of dislocations in their particles.Translated from Poroshkovaya Metallurgiya, No. 8(224), pp. 5–11, August, 1981.     

铝对复杂黄铜组织及性能的影响

用光学显微镜(OM)、硬度(HV)和万能试验机对添加不同铝含量(1.5%、2.0%、2.5%、3.0%、3.5%)的复杂黄铜(Cu-22.7Zn-Al-1.0Ni)组织与性能进行了研究.研究结果显示,铝能使合金α相区显著缩小、β相区增加,并起到细化α相、β相的作用,提高合金的抗拉强度、硬度.合金的机械性能随铝含量增加,其抗拉强度和屈服强度提高,而延伸率和冲击韧性下降,当铝含量为3.0%时,0.2 mm Y态板材硬度达到255 HV、抗拉强度达到820 MPa.     

等离子喷涂制备铁基非晶-纳米复合涂层

以一种多元素铁基非晶合金粉末(含C,Si,B,Cr,W,Mo,Ni,Fe等)作为喷涂材料,用大气等离子喷涂在316L不锈钢基体上制备涂层.用X射线衍射仪检测涂层的晶型结构,扫描电镜观察涂层的形貌,透射电镜观察涂层的微观组织结构,显微硬度仪测量涂层的显微硬度,纳米压痕仪测量涂层的硬度及弹性模量,并用谢乐公式计算了晶粒尺寸.结果表明:所制备的涂层均匀致密,与基体结合良好;涂层含有非晶和纳米颗粒;这种非晶-纳米复合涂层具有很高的硬度和弹性模量.     

铌对纳米晶Nd2Fe14B合金组织结构与磁性能的影响

采用熔体快淬及晶化退火工艺制备了单相Nd2Fe14B纳米晶合金。研究了添加Nb对Nd12.3Fe81.7-xNbxB6.0(x=0.5,1.0,1.5,2.0,2.5,3.0)系列合金的微观组织、磁性能和晶化行为的影响规律。结果表明:添加Nb可提高晶化温度并稳定非晶相;在退火晶化过程中,加入Nb后形成的析出相可以抑制晶粒长大,使晶粒细化且分布均匀,进而提高了材料的综合磁性能。通过对系列合金磁性能分析可知:Nd12.3Fe81.2Nb0.5B6.0合金在600℃退火处理10min后的磁性能最佳,磁能积(BH)m=141.13kJ.m-3,矫顽力Hci=867.95kA.m-1,剩磁Jr=1.02T。     

Effect of quenching in a magnetic field on the structure and properties of sintered magnets from an SmCo5 alloy powder

Conclusions Quenching in a magnetic field has a beneficial effect: It increases the coercive force of a magnet from a SmCo₅ alloy powder. Thermomagnetic treatment results in freezing of magnetic and phase- and-structure changes in magnets.Translated from Poroshkovaya Metallurgiya, No. 7 (259), pp. 37–42, July, 1984.