Fabrication of Titanium Aluminides via Powder-Cored Wire Arc Additive Manufacturing: Microstructural and Mechanical Characterization

Herein, an innovative powder-cored wire arc additive manufacturing (PC-WAAM) process is proposed to fabricate γ-TiAl thin-walled intermetallic alloy. The metallography, phase composition, and mechanical properties at different thin-wall locations are characterized. The results show that the alternatively distributed layer-like microstructure composed of α₂ (Ti₃Al) and γ (TiAl) phases is obtained along the building direction. The content of α₂ phase exhibits the tendency of decreasing from the bottom to top region. This unique microstructure characteristic is closely related to the typical thermal cycling history during deposition. Moreover, the tensile strength and microhardness of the top region are lower than the middle and bottom region. In general, the current PC-WAAM technique shows promising capability of fabricating γ-TiAl intermetallic alloy with low cost. This work becomes a valuable reference for understanding the evolution mechanism of microstructure and paves the way for the flexible and customized additive manufacturing of γ-TiAl alloy.     

Generation of uniform drops via through-hole arrays micromachined in stainless-steel plates

This study investigated the generation of oil drops using new symmetric and asymmetric through-hole-array devices made of stainless steel. The through-hole-array devices were built by piling up six stainless-steel plates, each having circular micro-holes with a diameter of 300 or 500 μm or micro-slots with a shorter line of 300 or 500 μm. Drops were generated by injecting a dispersed phase (refined soybean oil) via the through-hole array into a compartment filled with a continuous phase (Milli-Q water solution containing one of two emulsifiers). The drop detachment from symmetric and asymmetric through holes was observed in real time and analyzed. Uniform oil drops with average diameters of 1.0–4.1 mm and coefficients of variation of typically less than 6% were generated using symmetric and asymmetric through-hole-array devices. The resultant drop diameters for asymmetric through-hole arrays were significantly smaller than those for symmetric through-hole arrays. This paper also discusses experimental results regarding the effects of the microstructure, the dimensions of the through holes, and the type of emulsifier on drop generation and the resultant drop diameter.     

5083-H321铝合金板材搅拌摩擦焊缝组织演变

采用搅拌摩擦焊接法焊接了5083-H321铝合金板材,借助光学显微镜、扫描电镜、背散射电子衍射分析仪及取向显微成像分析技术对焊缝与母材的组织进行了对比性研究.结果表明,该合金板材的焊缝无宏观缺陷,焊缝成形区呈现出与母材明显不同的组织特征;搅拌摩擦焊使该合金板材中大量的小角度晶界转化为大角度晶界,母材和焊核区的晶粒尺寸分布范围分别为6-55 μm及15-30 μm,晶粒纵横比分布范围分别为2~8和15-3,焊核区呈现均匀化与等轴化的动态再结晶特征.     

水凝胶接触镜材料与三油酸甘油酯的亲合性

以N-乙烯吡咯烷酮、甲基丙烯酸羟乙酯以及甲基丙烯酸甲酯、甲基丙烯酸乙酯或者甲基丙烯酸丁酯为原料,采用本体共聚法制备共聚物水凝胶角膜接触镜材料,通过材料样品在三油酸甘油酯溶液中浸泡前后的浓度变化,计算沉积量,评价人眼泪液组分三油酸甘油酯在共聚物水凝胶角膜接触镜材料上的沉积作用.结果表明,三油酸甘油酯的沉积量随溶液浓度增大、沉积温度升高、沉积时间延长而增大;共聚物水凝胶材料中N-乙烯吡咯烷酮组分的含量越大,沉积量越大;而甲基丙烯酸甲酯、甲基丙烯酸乙酯或者甲基丙烯酸丁酯组分导致三油酸甘油酯的沉积量减小,以甲基丙烯酸甲酯最为明显.     

热致感应型形状记忆三元凝胶的制备与性能

选用疏水性单体丙烯酸十八酯（SA）和十一烯酸（HA）以及亲水性单体丙烯酰胺（AM）制备了三元共聚凝胶P（SA-co-AM-co-HA），通过X射线衍射、DSC、DMA等对三元凝胶的结构和性能进行了研究，发现三元凝胶形成了有序排列，这种有序排列会随着温度的变化发生可逆转变，从而使凝胶显示较好的形状记忆特性。     

碳纳米管对智能凝胶性能影响的研究

利用碳纳米管（CNTs）超强的力学性能将碳纳米管引入聚丙烯酸（PAA）凝胶网络中，制备出新型含碳纳米管的聚丙烯酸凝胶．实验证明其并不改变凝胶原有的离子响应性和pH响应性；力学强度测试表明，其与普通PAA凝胶相比机械性能明显提高．     

微量Ag对Al-Cu-Mg合金显微组织与力学性能的影响

研究了Ag元素对Al-8Cu-0．5Mg合金显微组织、室温及高温力学性能的影响。结果表明：均匀分布在铝基体{001}面和{111}面上共存的θ′和Ω（成分为Al2Cu）沉淀相能对含Ag合金起强化作用；而不含Ag的合金只有θ′一种沉淀相。含Ag合金中小尺寸以及近间距的θ′和Ω沉淀相提高了室温及高温下合金的屈服强度和拉伸强度。然而，与不含Ag的合金相比，由于这种小尺寸及近间距的θ′和Ω沉淀相在变形过程中具有与基体的内在不相容性，含银合金的伸长率降低。     

A Novel Drug Delivery System for Osteosarcoma Chemotherapy

1Introduction Osteosarcoma,35%ofhumanprimarybonecan cers,ishighlymalignantandtendstotransferandgrow permeantly.Chemotherapyisaneffectiveandbasicthera pyforosteosarcoma,buttheside effectofantineoplasticdrugslimitstheconcentrationofthemwhichinfluences thecu…