Loss of mechanical properties in vivo and bone–implant interface strength of AZ31B magnesium alloy screws with Si-containing coating

This work is to study the influence of heat treatment on microstrudture and mechanical properties of AZ31B magnesium alloy prepared by solid -state recycling. AZ31B magnesium alloy chips were recycled by hot extruding. Three different heat treatments were conducted for recycled alloy. Mechanical properties and microstructure of the recycled specimen and heat treated specimen were investigated. 300°C×2h annealing specimen exhibits finer grain due to static recrystallization, and microstructure of 400°C×2h annealing specimen becomes more coarse. 300°C×2h annealing treatment improves obviously strength and ductility of recycled alloy. Ultimate tensile strength of alloy decreases and elongation to failure increases after 400°C×2h annealing. Grain size, dislocation density and bonding of chips have an effect on the elongation of recycled materials. 190°C×8h ageing has no influence on microstructure and mechanical properties of recycled alloy.

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Theorical study on mechanical properties of AZ31B Magnesium alloy Sheets under multiaxial loading

Frattura ed Integrità Strutturale ◽

10.3221/igf-esis.38.18 ◽

2016 ◽

Vol 10 (38) ◽

pp. 135-140 ◽

Cited By ~ 1

Author(s):

A. Znaidi ◽

O. Daghfas ◽

S. Guellouz ◽

R. Nasri

Keyword(s):

Mechanical Properties ◽

Magnesium Alloy ◽

Multiaxial Loading ◽

Az31b Magnesium Alloy

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Friction Stir Welding of AZ31B Magnesium Alloy with 6061-T6 Aluminum Alloy: Influence of Processing Parameters on Microstructure and Mechanical Properties

Friction Stir Welding and Processing VIII ◽

10.1002/9781119093343.ch28 ◽

2015 ◽

pp. 259-266 ◽

Cited By ~ 1

Author(s):

B. Mansoor ◽

A. Dorbane ◽

G. Ayoub ◽

A. Imad

Keyword(s):

Mechanical Properties ◽

Aluminum Alloy ◽

Friction Stir Welding ◽

Magnesium Alloy ◽

Processing Parameters ◽

Az31b Magnesium Alloy ◽

Friction Stir ◽

Microstructure And Mechanical Properties

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Degradation and Biocompatibility of AZ31 Magnesium Alloy Implants In Vitro and In Vivo: A Micro-Computed Tomography Study in Rats

Materials ◽

10.3390/ma13020473 ◽

2020 ◽

Vol 13 (2) ◽

pp. 473 ◽

Cited By ~ 1

Author(s):

Naohiko Kawamura ◽

Yuya Nakao ◽

Rina Ishikawa ◽

Dai Tsuchida ◽

Masahiro Iijima

Keyword(s):

Computed Tomography ◽

Mechanical Properties ◽

Magnesium Alloy ◽

Mg Alloy ◽

Nanoindentation Test ◽

Mechanical Degradation ◽

Micro Computed Tomography ◽

Bone Implant ◽

Az31 Mg Alloy ◽

Degradation Rates

In current orthodontic practice, miniscrew implants (MSIs) for anchorage and bone fixation plates (BFPs) for surgical orthodontic treatment are commonly used. MSIs and BFPs that are made of bioabsorbable material would avoid the need for removal surgery. We investigated the mechanical, degradation and osseointegration properties and the bone-implant interface strength of the AZ31 bioabsorbable magnesium alloy to assess its suitability for MSIs and BFPs. The mechanical properties of a Ti alloy (TiA), AZ31 Mg alloy (MgA), pure Mg and poly-L-lactic acid (PLA) were investigated using a nanoindentation test. Also, pH changes in the solution and degradation rates were determined using immersion tests. Three-dimensional, high-resolution, micro-computed tomography (CT) of implants in the rat femur was performed. Biomechanical push-out testing was conducted to calculate the maximum shear strength of the bone-implant interface. Scanning electron microscopy (SEM), histological analysis and an evaluation of systemic inflammation were performed. MgA has mechanical properties similar to those of bone, and is suitable for implants. The degradation rate of MgA was significantly lower than that of Mg. MgA achieved a significantly higher bone-implant bond strength than TiA. Micro-CT revealed no significant differences in bone density or bone-implant contact between TiA and MgA. In conclusion, the AZ31 Mg alloy is suitable for both MSIs and BFPs.

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Comparison of the In Vivo Degradation Progress of Solid Magnesium Alloy Cylinders and Screw-Shaped Magnesium Alloy Cylinders in a Rabbit Model

Materials Science Forum ◽

10.4028/www.scientific.net/msf.638-642.742 ◽

2010 ◽

Vol 638-642 ◽

pp. 742-747 ◽

Cited By ~ 7

Author(s):

Nina von der Höh ◽

Dirk Bormann ◽

Arne Lucas ◽

Fritz Thorey ◽

Andrea Meyer-Lindenberg

Keyword(s):

Magnesium Alloy ◽

Pitting Corrosion ◽

Femoral Condyle ◽

Rabbit Model ◽

Degradation Behavior ◽

Gas Generation ◽

Cross Sectional ◽

Bone Implant ◽

Computed Tomograph

Resorbable magnesium alloy implants for osteosynthetic surgery would be advantageous to common implants of titanium or surgical steel as a second surgery for implant removal would become unnecessary. To influence the degradation progress, surface modifications are sensible. As plates and screws were used to stabilize fractures, the degradation behavior of threaded cylinders is of particular interest. Therefore each eight solid MgCa0.8 alloy cylinders (3 x 5 mm) with smooth and sandblasted surface, respectively, and eight screw-shaped, threaded MgCa0.8 cylinders (thread pitch 1.25 mm, length 5 mm) were inserted into the medial femoral condyle of adult New Zealand White rabbits. Implantation periods were three and six months, within which the animals were examined daily. To evaluate a possible gas generation radiographs were taken weekly. After euthanasia the bone-implant-compound was scanned in a µ-computed tomograph (µCT80, ScancoMedical). All implants were well tolerated. Smooth implants degraded slowly. The cross sectional area did not reduce obviously after three months implantation duration and only mildly after six months. Sandblasted implants showed the fastest degradation progress after both implantation periods with the most obvious generation of gas. Threaded cylinders revealed pitting corrosion at the thread pitches. They degrade faster than smooth implants but slower than sandblasted cylinders. In summary, surface modification influences the degradation behavior of resorbable magnesium alloy implants. Contrary to common materials, smooth surfaces seem to be favorable. Thread pitches of screw-shaped implants show pitting corrosion. To what extend this result affects future applications of resorbable screws has to be examined in further investigations.

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