Fracture toughness and tensile properties of two titanium alloys befor and after proton and neutron irradiations at 150°C

Two titanium alloys, the α+β Ti6Al4V and the α phase Ti5Al2.5Sn alloy, have been irradiated at 150°C with neutrons, in the reactor of the Atomic Energy Research Institute, in Budapest and with 590 MeV protons in the PIREX facility of the Paul Scherrer Institute, in Switzerland, to doses of the order of 0.15 dpa. The proton irradiation induced hydrogen as a product from spallation reactions. Some of the neutron irradiated specimens were previously loaded with 150 wppm hydrogen. The tensile and fracture toughness properties have been analyzed as a function of the measured hydrogen content. At low levels, hydrogen is not influencing significantly the tensile properties. The effect of irradiation on ductility and strength is more pronounced in the α+β Ti6Al4V, due to radiation induced phase instabilities. At a test temperature of 150°C, hydrogen levels up to 150 wppm have moderate effect on fracture toughness, in the unirradiated condition. For the irradiated specimens in both alloys, increasing the hydrogen content decreases the fracture toughness.The fracture toughness after irradiation is strongly reduced at room temperature, in both alloys.Два титанові сплави α+β Ті6A14V та α-фаза Ti5A12.5Sn були опромінені при 150ºС нейтронами в реакторі дослідницького Інституту ядерної енергії в Будапешті та 590 МеВ протонами на установці ПІРЕКС в Швейцарії до доз порядку 0.15 зна. Опромінення протонами зумовлює утворення водню як продукта розщеплення. Декілька опромінених нейтронами зразків були попередньо навантажені 150 wppm водню. Міцність на розтяг та в`язкість руйнування були проаналізовані як функція вмісту водню. При низьких рівнях водень не має суттєвого впливу на міцність на розтяг. Вплив опромінення на пластичність та на міцність більш виразний у сплаві α+β Ті6A14V внаслідок радіаційно-обумовленої фазової нестабільності. При температурі випробування в 150ºС водень у кількості 150wppm має помірний вплив на в`язкість руйнування в неопроміненному стані. Для опроміненних зразків в двох сталях зростання вмісту водню знижує в`язкість руйнування. В`язкість руйнування сильно зменьшується при кімнатній температурі в обох сплавах.Два титановых сплава α+β Ті6A14V и α-фаза Ti5A12.5Sn были облучены при 150ºС нейтронами в реакторе исследовательского Института ядерной энергии в Будапеште и 590 МэВ протонами на установке ПИРЕКС в Институте Поль- Шеррер, в Швейцарии до доз порядка 0.15 сна. Облучение протонами обусловливает образование водорода как продукта реакций расщепления. Несколько облученных нейтронами образцов были предварительно нагружены 150 wppm водорода. Прочность на растяжение и вязкость разрушения были проанализированы как функция содержания водорода. При низких уровнях водород не оказывает существенного влияния на прочность на растяжение. Влияние облучения на пластичность и прочность более выражено в α+β Ті6A14V вследствие радиационно-обусловленной фазовой нестабиль¬ ности. При температуре испытания в 150ºС водород в количестве 150 wppm оказывает умеренное влияние на вязкость разрушения в необлученном состоянии. Для облученных образцов в двух сталях увеличение содержания водорода понижает вязкость разрушения. Вязкость разрушения после облучения сильно уменьшается при комнатной температуре в обоих сплавах

The effect of pre-exercise galactose and glucose ingestion on high-intensity endurance cycling.

This study evaluated the effects of the pre-exercise (30 minutes) ingestion of galactose (Gal) or glucose (Glu) on endurance capacity as well as glycemic and insulinemic responses. Ten trained male cyclists completed 3 randomized high-intensity cycling endurance tests. Thirty minutes before each trial, cyclists ingested 1 L of either 40 g of glucose, 40 g of galactose, or a placebo in a double-blind manner. The protocol comprised 20 minutes of progressive incremental exercise (70-85% maximal power output [Wmax]); ten 90-second bouts at 90% Wmax, separated by 180 seconds at 55% Wmax; and 90% Wmax until exhaustion. Blood samples were drawn throughout the protocol. Times to exhaustion were longer with Gal (68.7 ± 10.2 minutes, p = 0.005) compared with Glu (58.5 ± 24.9 minutes), with neither being different to placebo (63.9 ± 16.2 minutes). Twenty-eight minutes after Glu consumption, plasma glucose and serum insulin concentrations were higher than with Gal and placebo (p < 0.001). After the initial 20 minutes of exercise, plasma glucose concentrations increased to a relative hyperglycemia during the Gal and placebo, compared with Glu condition. Higher plasma glucose concentrations during exercise, and the attenuated serum insulin response at rest, may explain the significantly longer times to exhaustion produced by Gal compared with Glu. However, neither carbohydrate treatment produced significantly longer times to exhaustion than placebo, suggesting that the pre-exercise ingestion of galactose and glucose alone is not sufficient to support this type of endurance performance

The effect of pre-exercise galactose and glucose ingestion on high-intensity endurance cycling.

This study evaluated the effects of the pre-exercise (30 minutes) ingestion of galactose (Gal) or glucose (Glu) on endurance capacity as well as glycemic and insulinemic responses. Ten trained male cyclists completed 3 randomized high-intensity cycling endurance tests. Thirty minutes before each trial, cyclists ingested 1 L of either 40 g of glucose, 40 g of galactose, or a placebo in a double-blind manner. The protocol comprised 20 minutes of progressive incremental exercise (70-85% maximal power output [Wmax]); ten 90-second bouts at 90% Wmax, separated by 180 seconds at 55% Wmax; and 90% Wmax until exhaustion. Blood samples were drawn throughout the protocol. Times to exhaustion were longer with Gal (68.7 ± 10.2 minutes, p = 0.005) compared with Glu (58.5 ± 24.9 minutes), with neither being different to placebo (63.9 ± 16.2 minutes). Twenty-eight minutes after Glu consumption, plasma glucose and serum insulin concentrations were higher than with Gal and placebo (p < 0.001). After the initial 20 minutes of exercise, plasma glucose concentrations increased to a relative hyperglycemia during the Gal and placebo, compared with Glu condition. Higher plasma glucose concentrations during exercise, and the attenuated serum insulin response at rest, may explain the significantly longer times to exhaustion produced by Gal compared with Glu. However, neither carbohydrate treatment produced significantly longer times to exhaustion than placebo, suggesting that the pre-exercise ingestion of galactose and glucose alone is not sufficient to support this type of endurance performance