The fabrication of shape memory alloy NiTi actuators by femtosecond laser ablation is presented. Processing parameters are examined and the effect of the ablation process on the shape memory material properties is assessed by electron microscopy and differential scanning calorimetry. It is shown that an efficient ablation process with negligible effect on the shape memory properties of the actuator material has been established with a cutting time of ~3 min per actuator. Two different actuator geometries are studied and their performances are compared by measurements of actuator stroke, force and resistance characteristics. A preconditioning procedure for stabilization of the resistance is presented, permitting an actuator control based on the intrinsic sensor effect. A wafer-level integration process of the actuators into silicon microgrippers is described. [2019-0032]

Titanium alloys are ideally suited for use in implant or osteosynthesis applications due to their good mechanical properties, corrosion resistance, and biocompatibility. In terms of higher strength applications, Ti–6Al–4V and Ti–6Al–7Nb are frequently used. However, both alloys contain the alloying elements aluminum and, in the former case, vanadium, which could have toxic effects on the human body. Therefore, in the present study, two novel, medium- to high-strength titanium alloys, Ti–0.44O–0.5Fe–0.08C–0.4Si–0.1Au and Ti–0.44O–0.5Fe–0.08C–2.0Mo, have been developed on the basis of CP-Titanium Grade 4. They only contain alloying elements, which are either already present in the human body or which are biocompatible. Dedicated thermo-mechanical treatments were developed for both alloys and the resulting mechanical properties were evaluated by tensile and (partly) fatigue tests with subsequent fracture surface analysis. Results reveal that these new alloys show excellent mechanical properties and, therefore, might be a possible alternative for Ti–6Al–4V for use in medical applications. Graphical abstract

Due to their outstanding mechanical properties, excellent corrosion resistance and biocompatibility titanium and titanium alloys are the first choice for medical engineering products. Alloys currently used for implant applications are Ti-6Al-4V (ELI) and Ti-6Al-7Nb. Both alloys belong to the class of (α+β)-alloys and contain aluminium as an alloying element. Aluminium is cytotoxic and can cause breast cancer. In addition, the stiffness of (α+β)-alloys is relatively high which can lead to stress shielding, bone degradation and implant loss. For this reason, second-generation titanium alloys like Ti-15Mo (solute-lean metastable β-alloy) and Ti-13Nb-13Zr (β-rich (α+β)-alloy) have been developed. However, their application in medical implants is limited due to a relatively low strength.Therefore, in the present study, the mechanical properties of Ti-15Mo and Ti-13Nb-13Zr have been optimised by thermomechanical treatments to achieve high strengths combined with low stiffnesses. Different phase compositions have been used, namely, α-, β- and ω-phase in Ti-15Mo and α-, β- and αʺ-phase in Ti-13Nb-13Zr. For Ti-15Mo, the required mechanical properties’ combination could not be achieved whereas Ti-13Nb-13Zr showed high strength and a low Young’s modulus after a dedicated thermo-mechanical treatment. This makes the latter alloy a good option for replacing the (α+β)-alloys in implant applications in the future.

Titanium (Ti) alloys combine outstanding mechanical properties with excellent corrosion resistance, making them desirable for challenging lightweight construction in the transportation industry. However, Ti production is energy consuming and expensive since the current method of extraction of Ti from the ore includes smelting, chlorination, and reduction by magnesium (Kroll process). Therefore, cost reduction is one of the driving factors for Ti research to broaden its field of application. This overview paper presents the basics of Ti metallurgy then discusses the conventional production route from Ti ore to semi-finished products and components. This includes ore beneficiation and processing, melting and remelting for ingot production, forging, casting, and machining of (semi-finished) products, scrap recycling, and additive manufacturing. The paper concludes with a brief overview of Ti applications in the transportation industry. Recent results of research projects carried out in the Titanium Research Group of the Institute for Materials Science (Technische Universität Braunschweig) are included to emphasize alloy development and thermomechanical treatments for microstructure optimization.

Since the Ti-2015 World Conference on Titanium held in San Diego, USA, research, development and applications of commercially pure titanium, titanium alloys and titanium aluminides have advanced considerably. In this plenary paper, information is provided on important achievements in the German titanium industry, governmental and non-governmental research organisations and universities from the last four years.