Imagazini yeMetal ePhezulu "iActa Materialia": Ukudinwa kweCrack yokuKhula kwindlela yokuziphatha yeMemory Memory Alloys

Iialloys zeememori zemilo (i-SMAs) zineempendulo ze-deformation yeempawu kwi-thermomechanical stimuli. I-Thermomechanical stimuli ivela kwiqondo lokushisa eliphezulu, ukufuduka, ukuguqulwa okuqinileyo-ukuqiniswa, njl. Ukutshintshwa kwesigaba se-cyclic ngokuphindaphindiweyo kukhokelela ekunyuseni kancinci kwi-dislocation, ngoko ke iindawo ezingatshintshiyo ziya kunciphisa ukusebenza kwe-SMA (ebizwa ngokuba yi-functional fatigue) kwaye ivelise i-microcracks, ekugqibeleni iya kubangela ukungaphumeleli komzimba xa inani likhulu ngokwaneleyo. Ngokucacileyo, ukuqonda indlela yokudinwa kobomi bezi zinto zixutyiweyo, ukusonjululwa kwengxaki yezinto ezilahliweyo ezixabisa kakhulu, kunye nokunciphisa uphuhliso lwemathiriyeli kunye nomjikelo woyilo lwemveliso konke kuya kuvelisa uxinzelelo olukhulu lwezoqoqosho.

Ukudinwa kwe-Thermo-mechanical akukhange kuhlolwe kakhulu, ngakumbi ukungabikho kophando malunga nokudinwa kwe-crack propagation phantsi kwemijikelo ye-thermo-mechanical. Ekuphunyezweni kwangaphambili kwe-SMA kwi-biomedicine, ugxininiso lophando lokukhathala yayibubomi obupheleleyo beesampuli "ezingenasiphako" phantsi kwemithwalo ye-cyclic mechanical. Kwizicelo ezinejometri encinci ye-SMA, ukukhathala ukukhula kwe-crack kunempembelelo encinci ebomini, ngoko uphando lujolise ekuthinteleni ukuqaliswa kwe-crack kunokulawula ukukhula kwayo; ekuqhubeni, ekunciphiseni ukungcangcazela kunye nezicelo zokufunxa amandla, kuyafuneka ukuba ufumane amandla ngokukhawuleza. Amacandelo e-SMA adla ngokuba makhulu ngokwaneleyo ukugcina ukusasazwa okubalulekileyo kokuqhekeka phambi kokusilela. Ngoko ke, ukuhlangabezana nokuthembeka okuyimfuneko kunye neemfuno zokhuseleko, kuyimfuneko ukuqonda ngokupheleleyo kunye nokulinganisa ukuziphatha kokukhathala kokukhula kwe-crack ngokusebenzisa indlela yokunyamezela umonakalo. Ukusetyenziswa kweendlela zokunyamezela umonakalo oxhomekeke kwingcamango ye-fracture mechanics kwi-SMA ayilula. Xa kuthelekiswa nesinyithi sezakhiwo zemveli, ubukho benguqu yesigaba esibuyiselwa umva kunye nokudibanisa i-thermo-mechanical kubangela imingeni emitsha ukuchaza ngokufanelekileyo ukudinwa kunye nokwaphuka okukhulu kwe-SMA.

Abaphandi abavela kwiYunivesithi yaseTexas A&M eUnited States baqhube imifuniselo yokukhula komatshini kunye nokudinwa okuqhutywa kukudinwa kwi-Ni50.3Ti29.7Hf20 superalloy okokuqala, kwaye bacebise imbonakalo yomthetho wamandla edibeneyo yaseParis enokuthi isetyenziselwe Fit ukudinwa. izinga lokukhula kokuqhekeka phantsi kweparamitha enye. Kucingelwa koku ukuba ubudlelwane obunamandla kunye nesantya sokukhula kwe-crack bunokufakwa phakathi kweemeko ezahlukeneyo zokulayisha kunye nokulungelelaniswa kwejometri, enokusetyenziswa njengenkcazo edibeneyo enokubakho yokukhula kwe-deformation crack kwii-SMAs. Iphepha eliyeleleneyo lapapashwa kwi-Acta Materialia enesihloko esithi "Inkcazo edibeneyo yomatshini kunye ne-actuation fatigue crack growth in shape memory alloys".

Ikhonkco lephepha:

https://doi.org/10.1016/j.actamat.2021.117155

Uphononongo lufumene ukuba xa i-Ni50.3Ti29.7Hf20 ialloy iphantsi kovavanyo lwe-uniaxial tensile kwi-180 ℃, i-austenite ikhubazeke kakhulu phantsi kwenqanaba loxinzelelo oluphantsi ngexesha lenkqubo yokulayisha, kwaye imodyuli yoMncinci imalunga ne-90GPa. Xa uxinzelelo lufikelela malunga ne-300MPa Ekuqaleni kokuguqulwa kwesigaba esilungileyo, i-austenite iguqulela kwi-martensite ebangelwa uxinzelelo; xa kuthululwa, i-martensite eyenziwe ngoxinzelelo ikakhulu ingena kwi-elastic deformation, kunye nemodyuli ye-Young emalunga ne-60 GPa, kwaye emva koko iguqule umva kwi-austenite. Ngokudityaniswa, izinga lokudinwa lokukhula kwe-crack yemathiriyeli yolwakhiwo lifakelwe kwimbonakalo yomthetho wamandla wohlobo lwaseParis.
Umfanekiso we-Fig.1 we-BSE we-Ni50.3Ti29.7Hf20 ingxubevange yenkumbulo yobushushu obuphezulu kunye nobungakanani bokuhanjiswa kwamasuntswana oksidi
Umfanekiso we-2 TEM umfanekiso we-Ni50.3Ti29.7Hf20 inkumbulo yobushushu obuphezulu bemilo yengxubevange emva konyango lobushushu kwi-550℃×3h
Umzobo 3 Ubudlelwane phakathi kwe-J kunye ne-da/dN yokudinwa komatshini ukukhula kokuqhekeka komzekelo we-NiTiHf DCT kwi-180℃

Kwimifuniselo ekweli nqaku, kungqinwe ukuba le fomula inokulingana nedatha yokudinwa kwesantya sokukhula kwayo yonke imifuniselo kwaye inokusebenzisa iseti efanayo yeeparamitha. I-exponent yomthetho wamandla m malunga ne-2.2. Uhlalutyo lwe-fracture yokudinwa lubonisa ukuba zombini i-mechanical crack propagation kunye nokuqhubela phambili kwe-crack yi-quasi-cleavage fractures, kwaye ubukho rhoqo bomphezulu we-hafnium oxide buye baqinisa ukuxhathisa ukuqhekeka. Iziphumo ezifunyenweyo zibonisa ukuba ukubonakaliswa komthetho wamandla ombane omnye kunokufikelela ukufana okufunekayo kuluhlu olubanzi lweemeko zokulayisha kunye nokulungelelaniswa kwejometri, ngaloo ndlela inikezela inkcazo edibeneyo yokudinwa kwe-thermo-mechanical of shape memory alloys, ngaloo ndlela kuqikelelwa amandla okuqhuba.
Isazobe 4 SEM umfanekiso wokwaphuka komzekelo we-NiTiHf DCT emva kwe-180℃ umfuniselo wokukhula wokudinwa kumatshini
Umfanekiso we-5 Fracture SEM umfanekiso womzekelo we-NiTiHf DCT emva kokuqhuba umfuniselo wokudinwa wokukhula kwe-crack phantsi komthwalo ongatshintshiyo we-250 N.

Isishwankathelo, eli phepha liqhuba imifuniselo esulungekileyo yoomatshini kunye nokudinwa kokukhula kwi-nickel-rich NiTiHf i-alloys yenkumbulo yobushushu obuphezulu okokuqala. Ngokusekwe kuhlanganiso lomjikelo, iParis-type power-law-law growth expression iyacetywa ukuba ilingane isantya sokukhula sokudinwa komfuniselo ngamnye phantsi kweparameter enye.


Ixesha lokuposa: Sep-07-2021