Stress corrosion cracking(SCC)may lead to brittle,unexpected failure of medical devices.However,available researches are limited to Mg-based biodegradable metals(BM)and pure Zn.The stress corrosion behaviors of newly-...Stress corrosion cracking(SCC)may lead to brittle,unexpected failure of medical devices.However,available researches are limited to Mg-based biodegradable metals(BM)and pure Zn.The stress corrosion behaviors of newly-developed Zn alloys remain unclear.In the present work,we conducted slow strain rate testing(SSRT)and constant-load immersion test on a promising Zn-0.8 wt%Li alloy in order to investigate its SCC susceptibility and examine its feasibility as BM with pure Zn as control group.We observed that Zn-0.8 wt%Li alloy exhibited low SCC susceptibility.This was attributed to variations in microstructure and deformation mechanism after alloying with Li.In addition,both pure Zn and Zn-0.8 wt%Li alloy did not fracture over a period of 28 days during constant-load immersion test.The magnitude of applied stress was close to physiological condition and thus,we proved the feasibility of both materials as BM.展开更多
Healing of fractures or bone defects is significantly hindered by overactivated osteoclasts and inhibited osteogenesis in patients with abnormal bone metabolism.Current clinical approaches using titanium alloys or sta...Healing of fractures or bone defects is significantly hindered by overactivated osteoclasts and inhibited osteogenesis in patients with abnormal bone metabolism.Current clinical approaches using titanium alloys or stainless steel provide mechanical support but have no biological effects on bone regeneration.Therefore,designing and fabricating degradable metal materials with sufficient mechanical strength and bidirectional regulation of both osteoblasts and osteoclasts is a substantial challenge.Here,this study first reported an adaptive biodegradable Zn-0.8 Mg alloy with bidirectional regulation of bone homeostasis,which promotes osteogenic differentiation by activating the Pi3k/Akt pathway and inhibits osteoclast differentiation by inhibiting the GRB2/ERK pathway.The anti-osteolytic ability of the Zn-0.8 Mg alloy was verified in a mouse calvarial osteolysis model and its suitability for internal fracture fixation with high-strength screws was confirmed in the rabbit femoral condyle fracture model.Furthermore,in an aged postmenopausal rat femoral condyle defect model,3D printed Zn-0.8 Mg scaffolds promoted excellent bone regeneration through adaptive structures with good mechanical properties and bidirectionally regulated bone metabolism,enabling personalized bone defect repair.These findings demonstrate the substantial potential of the Zn-0.8 Mg alloy for treating fractures or bone defects in patients with aberrant bone metabolism.展开更多
Environmentally degradable Zn-0.8Mn alloy is highly ductile,which lays the foundation for developing high-performance Zn-Mn-based alloys.However,not only constitutive equation of this alloy is unknown,but also its dyn...Environmentally degradable Zn-0.8Mn alloy is highly ductile,which lays the foundation for developing high-performance Zn-Mn-based alloys.However,not only constitutive equation of this alloy is unknown,but also its dynamic recrystallization(DRX)behavior is unclear,which makes optimization of hot pro-cessing parameters of this alloy almost dependent on trial-and-error.This work aims to tackle these prob-lems.The constitutive equation was deduced to be˙ε=1.38×10^(12)×[sinh(0.009σ)]^(8)exp(-135150/RT).A processing map of the alloy was obtained for the first time,which shows that it has excellent hot formability with narrow instability zones.At a final true strain of 0.8,the volume fraction of DRX grains increased from 37%to 79%with temperature increasing from 150℃to 350℃and strain rate decreas-ing from 10 s^(−1)to 10^(-3)s^(−1).Discontinuous DRX(DDRX),continuous DRX(CDRX),twinning-induced DRX(TDRX),and particle stimulated nucleation(PSN)were activated during hot compressions.DDRX was al-ways the main mechanism.TDRX was completely suppressed at 300℃and above.PSN arose from dis-persed MnZn 13 particles.Furthermore,Zn-0.8Mn alloy exhibited elevated-temperature strengths better than pure Zn and Zn-Al-based alloys.At 300℃and 0.1 s^(−1),its peak stress was 1.8 times of pure Zn,owing to MnZn 13 particles of 277±79 nm impeding the motion of grain boundaries and dislocations.展开更多
基金supported by National Natural Science Foundation of China(Grant No.51931001).
文摘Stress corrosion cracking(SCC)may lead to brittle,unexpected failure of medical devices.However,available researches are limited to Mg-based biodegradable metals(BM)and pure Zn.The stress corrosion behaviors of newly-developed Zn alloys remain unclear.In the present work,we conducted slow strain rate testing(SSRT)and constant-load immersion test on a promising Zn-0.8 wt%Li alloy in order to investigate its SCC susceptibility and examine its feasibility as BM with pure Zn as control group.We observed that Zn-0.8 wt%Li alloy exhibited low SCC susceptibility.This was attributed to variations in microstructure and deformation mechanism after alloying with Li.In addition,both pure Zn and Zn-0.8 wt%Li alloy did not fracture over a period of 28 days during constant-load immersion test.The magnitude of applied stress was close to physiological condition and thus,we proved the feasibility of both materials as BM.
基金supported by the National Natural Science Foundation of China(Grant Nos.32222042,82225031,82172464,82172453,81972086,52171237,and 52175274)the National Key Research and Development Program of China(Grant No.2023YFC2509600)+2 种基金the Program of Shanghai Excellent Academic Leader(Grant No.22XD1401900)the Shuguang Plan Project and the Shanghai Rising-Star Program(Grant No.21QA1405500)the Non-profit Central Research Institute Fund of National Research for Family Planning(Grant No.2022GJM03).
文摘Healing of fractures or bone defects is significantly hindered by overactivated osteoclasts and inhibited osteogenesis in patients with abnormal bone metabolism.Current clinical approaches using titanium alloys or stainless steel provide mechanical support but have no biological effects on bone regeneration.Therefore,designing and fabricating degradable metal materials with sufficient mechanical strength and bidirectional regulation of both osteoblasts and osteoclasts is a substantial challenge.Here,this study first reported an adaptive biodegradable Zn-0.8 Mg alloy with bidirectional regulation of bone homeostasis,which promotes osteogenic differentiation by activating the Pi3k/Akt pathway and inhibits osteoclast differentiation by inhibiting the GRB2/ERK pathway.The anti-osteolytic ability of the Zn-0.8 Mg alloy was verified in a mouse calvarial osteolysis model and its suitability for internal fracture fixation with high-strength screws was confirmed in the rabbit femoral condyle fracture model.Furthermore,in an aged postmenopausal rat femoral condyle defect model,3D printed Zn-0.8 Mg scaffolds promoted excellent bone regeneration through adaptive structures with good mechanical properties and bidirectionally regulated bone metabolism,enabling personalized bone defect repair.These findings demonstrate the substantial potential of the Zn-0.8 Mg alloy for treating fractures or bone defects in patients with aberrant bone metabolism.
基金This work was financially supported by the National Natural Science Foundation of China(No.52071028)the Fundamental Research Funds for the Central Universities(Project No.FRF-TP-19-022A3Z).
文摘Environmentally degradable Zn-0.8Mn alloy is highly ductile,which lays the foundation for developing high-performance Zn-Mn-based alloys.However,not only constitutive equation of this alloy is unknown,but also its dynamic recrystallization(DRX)behavior is unclear,which makes optimization of hot pro-cessing parameters of this alloy almost dependent on trial-and-error.This work aims to tackle these prob-lems.The constitutive equation was deduced to be˙ε=1.38×10^(12)×[sinh(0.009σ)]^(8)exp(-135150/RT).A processing map of the alloy was obtained for the first time,which shows that it has excellent hot formability with narrow instability zones.At a final true strain of 0.8,the volume fraction of DRX grains increased from 37%to 79%with temperature increasing from 150℃to 350℃and strain rate decreas-ing from 10 s^(−1)to 10^(-3)s^(−1).Discontinuous DRX(DDRX),continuous DRX(CDRX),twinning-induced DRX(TDRX),and particle stimulated nucleation(PSN)were activated during hot compressions.DDRX was al-ways the main mechanism.TDRX was completely suppressed at 300℃and above.PSN arose from dis-persed MnZn 13 particles.Furthermore,Zn-0.8Mn alloy exhibited elevated-temperature strengths better than pure Zn and Zn-Al-based alloys.At 300℃and 0.1 s^(−1),its peak stress was 1.8 times of pure Zn,owing to MnZn 13 particles of 277±79 nm impeding the motion of grain boundaries and dislocations.
