不同涂层镁合金兔下颌骨植入的生物相容性研究

目的：采用微弧氧化的方法,对镁合金进行表面处理,得到两种不同涂层镁合金（分别为钙磷涂层镁合金及钙磷银涂层镁合金）并进行兔下颌骨内植入试验,以评价微弧氧化所得不同涂层镁合金及未处理镁合金的生物相容性。方法：采用微弧氧化得到的两种镁合金植入体及未处理镁合金在无菌手术条件下,植入哈尔滨大白兔的下颌骨内,4、8、12周分批处死后取材。本文主要通过对4、8、12周组的肝肾病理切片检测,描述植入材料的生物相容性。结果：所有实验动物均进入数据分析阶段,三种镁合金植入物均未对实验动物的肝、肾产生损害。结论：三种镁合金植入物的肝、肾病理学检测,均未发现对肝、肾造成不良影响,提示植入材料具有良好的生物相容性。一定剂量银离子的加入是安全的。这为镁合金表面改性方面的研究特别是在骨修复及骨固定方面的应用提供新的理论基础。     

Microstructural Evolution and an Improved Dynamic Recrystallization Kinetic Model of a Ni-Cr-Mo Alloy in Hot Deformation

Microstructural evolution and dynamic recrystallization (DRX) behaviors of a Ni-Cr-Mo alloy were researched utilizing hot compressive experiments. The changed features of dislocation, subgrain and grain structure correlating to forming parameters were examined by transmission electron microscope (TEM) and electron backscatter diffraction (EBSD). Results illustrate that the consumption of dislocation and the coarsening of substructure/DRX grain are prominently enhanced with an increased forming temperature. However, the annihilation/interaction of dislocation and the expansion of subgrain/DRX grain boundary can be limited at a larger strain rate. Meanwhile, considering the discrepancy in DRX variation rates concerning the strain rate’s ranges, an improved DRX kinetic model was developed. Compared to the classical DRX kinetic model, the good consistency between the forecasted and tested results demonstrates that the established improved DRX kinetic model can precisely characterize the DRX features of the Ni-Cr-Mo alloy over a wide strain rate range. Additionally, the EBSD’s quantitative statistical results proved that the variation of DRX grain size can be supremely defined as the power formulation of the forming temperature and strain rate.     

Microstructure Evolution and Deformation Mechanisms of As-Cast Antibacterial Ti6Al4V-5Cu Alloy for Isothermal Forging Process

The hot workability behavior of antibacterial Ti6Al4V-5Cu alloy was investigated using a hot compression experiment in the temperature range of 790–1040 °C and strain rate of 10⁻³–10 s⁻¹ with a strain of 0.4. The deformation behavior of the alloy was characterized by Gleeble 3800 compression experiment, and the relationship among deformed microstructures and deformation parameters was established. The deformations of Ti6Al4V-5Cu alloy were temperature and strain rate-dependent. Higher temperature and lower strain rate made power dissipation efficiency (η) increase and reach 89%. The activation energies (Q) in the dual-phase (α + β) and single β phase regions were calculated as 175.43 and 159.03 kJ mol⁻¹, respectively. In the dual (α + β) phase region, with an increase in strain rate, flow-softening behavior was dominated, however in the single β phase region such as processing at 940 °C. Flow stress increased slightly in which work-hardening behavior was dominated (especially between strain rates of 10⁻³–1 s⁻¹). The deformation at various conditions exhibited different stress-strain profiles, providing an insight that work hardening and flow softening coexisted in Ti6Al4V-5Cu alloy. The relative intensity of oscillatory change in flow stress profile decreased as the strain rate decreased. The hot workability of Ti6Al4V-5Cu alloy was also accessed from the viewpoint of the sub-grain structure.     

Microstructures and Soft Magnetic Properties of Fe73.5−xCu1Nb3Si13.5B9Gdx (x = 0–1.5) Alloys

In this experiment, the rare earth Gd element was added to Finemet alloy to observe the microstructure and soft magnetic properties. The experimental results showed that the samples with the addition of 0.5% Gd and 1.0% Gd can be quenched and cast normally, and the M_S of Fe₇₃Cu₁Nb₃Si_13.5B₉Gd_0.5 alloy was 10.41% higher than that of Finemet. After annealing, crystal grains of about 10 nm were formed. The μ_i and μ_m values of Fe₇₃Cu₁Nb₃Si_13.5B₉Gd_0.5 alloy were 25.51% and 22.23% higher, respectively, and the coercivity H_C was reduced by 12.19% compared to Finemet. At 1 kHz, the μ_e value of Fe₇₃Cu₁Nb₃Si_13.5B₉Gd_0.5 alloy at room temperature was 14.57% higher than that of Finemet, while the μ_e reached 162.34 k and 142.42 k at 90 °C and 150 °C (24% and 29.51% higher, respectively). The Fe_72.5Cu₁Nb₃Si_13.5B₉Gd_1.0 alloy had the best performance at 100 kHz, with higher μ_e values than Finemet across the ambient temperature range of 30 °C to 150 °C. After tension annealing, the μ_e values of Fe_72.5Cu₁Nb₃Si_13.5B₉Gd_1.0 alloy were 20–30% higher than those of Finemet.     

Electrochemical Evaluation of Stress Corrosion Cracking Susceptibility of Ti-6Al-3Nb-2Zr-1Mo Alloy Welded Joint in Simulated Deep-Sea Environment

Titanium alloys have high specific strength and excellent corrosion resistance and have been applied in deep-sea engineering fields. However, stress corrosion cracking may become one of the biggest threats to the service safety of a high-strength titanium alloy, as well as its weldment. In this work, stress corrosion cracking of a gas-tungsten-arc-welded Ti-6Al-3Nb-2Zr-1Mo (Ti6321) alloy influenced by the applied potentials in simulated deep-sea and shallow-sea environments was investigated by combining slow strain rate testing with electrochemical measurements. The results showed that the service environment and applied potential have a substantial effect on the stress corrosion cracking behavior of the Ti6321 welded joint. The Ti6321 welded joint exhibited higher stress corrosion susceptibility in a simulated deep-sea environment and at a strong polarization level owing to the diminishing protection of the passive film under passivation inhibition and the enhancement of the hydrogen effect. The fracture of a Ti6321 welded joint in the weld material could be attributed to the softening effect of the thick secondary α within the coarse-grained martensite. The electrochemical evaluation model of stress corrosion cracking susceptibility of a Ti6321 welded joint in a simulated marine environment was established by adding the criterion in the passivation region based on the literature model, and four potential regions corresponding to different stress corrosion cracking mechanisms were classified and discussed. Our study provides useful guidance for the deep-sea engineering applications of Ti6321 alloys and a rapid assessment method of stress corrosion risk.     

Deep Cryogenic Treatment Characteristics of a Deformation-Processed Cu-Ni-Co-Si Alloy

This paper investigated the influence of deep cryogenic treatments (DCT) on the tensile strength, elongation to fracture and conductivity of a deformation-processed Cu-Ni-Co-Si alloy. The tensile properties were measured using a mechanical testing machine. The conductivity was evaluated using a low-resistance tester. The microstructure and precipitated phases were analyzed using scanning electron microscopy (SEM), transmission electron microscopy (TEM), an energy dispersive spectrometer (EDS) and an X-ray diffractometer (XRD). The tensile strength, elongation to fracture and conductivity of the Cu-1.34Ni-1.02Co-0.61Si alloy before and after cold rolling at 47% reduction increased with increasing DCT time and tended to be stable at about 36 h. The microstructure became more uniform after the DCT. The grain size was refined and was smallest after DCT for 48 h. The DCT promoted the precipitation of the solid solution elements Ni, Co and Si from the Cu matrix to form many fine and evenly distributed 20–70 nm spherical second-phase particles in the grains and grain boundaries.     

钛锆合金粉末激光立体成形试件的机械性能

目的：研究口腔修复体用激光立体成形钛锆合金的力学性能。方法：按照金属拉伸试验的要求，分别制作铸造成形和激光成形的试件，采用拉伸试验机测定抗拉强度、屈服强度以及延伸率。结果：激光立体成形制备的钛锆试件的抗拉强度为940MPa，屈服强度为890MPa，延伸率为7．5％；铸造成形的钛锆合金抗拉强度为795MPa，屈服强度为657MPa，延伸率为22％。结论：与常规铸造成形的牙科钛锆合金相比，激光立体成形的钛锆合金具有更好的抗拉强度和屈服强度，延伸率虽然偏低，但能满足口腔修复用合金的要求。     

Prerequisites for magnetic resonance image-guided interventions and endoscopic surgery

Summary

Our purpose was to evaluate technological prerequisites and predural principles that enable easy, precise and reproducible magnetic resonance imaging control of interventional procedures, such as biopsy and aspiration of neoplasm or local interstitial drug instillation in adequate time and with the required safety. New MR compatible needles, trocars/cannulae, endoscopes and ancillary equipment were developed or evaluated in collaboration with industry. Sequences, study protocols and the strategies of performing the procedure within the environment of an interventional MRI suite were conceptualized and tested. In 80 patients interventions such as aspiration biopsy, peridural corticoid injection at spinal nerve roots and intratumoural ethanol instillation were performed successfully.     

Endoscopic Foreheadplasty: Temporary vs. Permanent Fixation

The introduction of fiberoptic endoscopes has fostered the development of minimally invasive aesthetic facial plastic surgery. The application of this new technology is most widely used in rejuvenation of the mildly to moderately ptotic brow. The concept of endoscopic foreheadplasty is based upon the following maneuvers. First, a sub- or supraperiosteal dissection of the parietal, occipital, and frontal scalp to the level of the superior and lateral orbital rims and zygomatic arch must be accomplished. Second, incision and release of the superior and lateral orbital periosteum are performed. Third, selective myotomies of the brow depressor muscles are completed. These maneuvers allow the brow to be permanently elevated into a desired position following fixation and healing. A significant limitation of this procedure appears to be the ability to predict the long-term forehead and brow elevation. We believe that permanent fixation is one of the best methods to ensure that the desired elevation is maintained. We contrast two series of patients, one with temporary fixation technique and the other with permanent fixation. We review the results and discuss the rationale and advantages of permanent fixation.     

镍钛记忆合金锁骨钩环抱器治疗新鲜重度肩锁关节脱位

目的 评估镍钛记忆合金锁骨钩环抱器治疗新鲜重度肩锁关节脱位的临床疗效。方法 选择16例新鲜重度肩锁关节脱位患者，其中3例合并锁骨远端骨折，应用镍钛记忆合金锁骨钩环抱器治疗并进行临床疗效观察。随访6～12个月，平均7.6个月。结果 所有患者肩关节肌肉无萎缩，外观正常，肩关节活动范围正常，x线片示无再脱位征象。采用Karlsson术后疗效分级：A级15例，B级1例。结论 镍钛记忆合金锁骨钩环抱器治疗新鲜重度肩锁关节脱位创伤小，简便易行，疗效好，对合并锁骨远端骨折病人更具有独特优点，具有临床推广应用价值。