Ama-alloys enkumbulo yomumo (ama-SMA) anempendulo yokuguquguquka kwesici ku-thermomechanical stimuli. I-Thermomechanical stimuli ivela ekushiseni okuphezulu, ekufudukeni, ekuguquleni okuqinile kuya kokuqinile, njll. (isigaba esiphezulu sezinga lokushisa eliphezulu sibizwa ngokuthi i-austenite, futhi isigaba se-low-order esiphansi sibizwa ngokuthi i-martensite). Ukuguqulwa okuphindaphindiwe kwesigaba se-cyclic kuholela ekwandeni kancane kancane kokuhlukaniswa, ngakho izindawo ezingaguquki zizonciphisa ukusebenza kwe-SMA (okubizwa ngokuthi ukukhathala okusebenzayo) futhi zikhiqize ama-microcracks, okuzogcina kuholele ekuhlulekeni ngokomzimba lapho inombolo inkulu ngokwanele. Ngokusobala, ukuqonda indlela yokuphila yokukhathala yalezi zingxubevange, ukuxazulula inkinga yezinsalela zezingxenye ezibizayo, nokunciphisa ukuthuthukiswa kwezinto ezibonakalayo kanye nomjikelezo wokuklama umkhiqizo konke kuzodala ingcindezi enkulu yezomnotho.
Ukukhathala kwe-Thermo-mechanical akuzange kuhlolwe ngokwezinga elikhulu, ikakhulukazi ukuntuleka kocwaningo mayelana nokusakazwa kwe-crack yokukhathala ngaphansi kwemijikelezo ye-thermo-mechanical. Ekuqalisweni kokuqala kwe-SMA ku-biomedicine, ukugxila kocwaningo lokukhathala kwakuyimpilo ephelele yamasampuli "angenasici" ngaphansi kwemithwalo yemishini eyi-cyclic. Kuzinhlelo zokusebenza ezine-geometry encane ye-SMA, ukukhula kwe-crack ukukhathala kunomphumela omncane empilweni, ngakho ucwaningo lugxile ekuvimbeleni ukuqaliswa kokuqhekeka kunokulawula ukukhula kwayo; ekushayeleni, ekunciphiseni ukudlidliza kanye nezicelo zokumuncwa amandla, kuyadingeka ukuthola amandla ngokushesha. Izingxenye ze-SMA zivame ukuba zinkulu ngokwanele ukugcina ukusakazeka okubalulekile kokuqhekeka ngaphambi kokuhluleka. Ngakho-ke, ukuze kuhlangatshezwane nezidingo ezidingekayo zokwethembeka nezokuphepha, kuyadingeka ukuqonda ngokugcwele kanye nokulinganisa ukuziphatha kokukhathala kokukhula kwe-crack ngokusebenzisa indlela yokubekezelela umonakalo. Ukusetshenziswa kwezindlela zokubekezelela umonakalo ezincike kumqondo womshini wokuphuka ku-SMA akulula. Uma kuqhathaniswa nezinsimbi zesakhiwo esivamile, ukuba khona koshintsho lwesigaba esihlehliswayo kanye nokuhlangana kwe-thermo-mechanical kubangela izinselele ezintsha ukuchaza ngempumelelo ukukhathala nokuphuka okuchichimayo kwe-SMA.
Abacwaningi abavela eNyuvesi yase-Texas A&M e-United States benze izivivinyo eziqinile zokukhula kwe-crack yokukhathala kwemishini kanye neqhutshwa ukukhathala ku-Ni50.3Ti29.7Hf20 superalloy okokuqala ngqa, futhi bahlongoza isisho somthetho wamandla wohlobo lwase-Paris esisekelwe ngokuphelele esingasetshenziselwa i-Fit the fatigue. izinga lokukhula kwe-crack ngaphansi kwepharamitha eyodwa. Kucatshangelwa kulokhu ukuthi ubudlelwano obunamandla nezinga lokukhula kwe-crack bungafakwa phakathi kwezimo ezihlukene zokulayisha kanye nokuhlelwa kwejiyomethri, okungasetshenziswa njengencazelo engaba namandla ehlanganisiwe yokukhula kwe-deformation crack kuma-SMA. Iphepha elihlobene lashicilelwa ku-Acta Materialia elinesihloko esithi “Incazelo ehlanganisiwe yokukhula kokukhathala komshini kanye ne-actuation kuma-alloys enkumbulo yomumo”.
Isixhumanisi sephepha:
https://doi.org/10.1016/j.actamat.2021.117155
Ucwaningo luthole ukuthi uma ingxubevange ye-Ni50.3Ti29.7Hf20 ingaphansi kokuhlolwa kwe-uniaxial tensile ku-180℃, i-austenite ikhubazeka kakhulu ngokunwebeka ngaphansi kwezinga eliphansi lokucindezeleka phakathi nenqubo yokulayisha, kanti i-Young's modulus cishe i-90GPa. Lapho ukucindezeleka kufinyelela mayelana ne-300MPa Ekuqaleni kokuguqulwa kwesigaba esihle, i-austenite iguqulela ku-martensite ebangelwa ukucindezeleka; lapho kuthululwa, i-martensite ebangelwa ukucindezeleka ikakhulukazi iba nokuwohloka okunwebekayo, nge-modulus ye-Young engaba ngu-60 GPa, bese iguqulela emuva ku-austenite. Ngokuhlanganisa, izinga lokukhula kwe-crack yokukhathala lezinto zesakhiwo lifakelwe isisho somthetho wamandla wohlobo lwase-Paris.
Umfanekiso we-Fig.1 BSE we-Ni50.3Ti29.7Hf20 ingxubevange yenkumbulo yomumo wokushisa okuphezulu nokusabalalisa usayizi wezinhlayiya ze-oxide
Umfanekiso 2 TEM isithombe se-Ni50.3Ti29.7Hf20 ingxubevange yenkumbulo yokushisa okuphezulu ngemuva kokwelashwa kokushisa ku-550℃×3h
Umdwebo 3 Ubudlelwano phakathi kwe-J kanye ne-da/dN yokukhula kokukhathala kokusebenza kwesampula ye-NiTiHf DCT ku-180℃
Ocwaningweni kulesi sihloko, kufakazelwa ukuthi le fomula ingalingana nedatha yezinga lokukhula kokukhathala kusuka kukho konke ukuhlola futhi ingasebenzisa isethi efanayo yamapharamitha. I-exponent yomthetho wamandla m icishe ibe ngu-2.2. Ukuhlaziywa kokukhathala kokuphuka kubonisa ukuthi kokubili ukusakazeka kokuqhekeka komshini kanye nokusabalalisa ukuqhekeka kokushayela kuwukuqhekeka kwe-quasi-cleavage, futhi ukuba khona njalo kwe-surface hafnium oxide kuye kwandisa ukumelana nokusakazeka kokuqhekeka. Imiphumela etholiwe ibonisa ukuthi isisho esisodwa somthetho wamandla we-empirical singafinyelela ukufana okudingekayo ebangeni elibanzi lezimo zokulayisha nokulungiselelwa kwejiyomethri, ngaleyo ndlela kunikeze incazelo ehlangene yokukhathala kwe-thermo-mechanical yamaalloyi enkumbulo yomumo, ngaleyo ndlela kulinganise amandla okushayela.
Umfanekiso 4 SEM wesithombe sokuphuka kwesampula ye-NiTiHf DCT ngemva kokuhlolwa kokukhula kokukhathala kokukhathala okungu-180℃
Umfanekiso we-5 Fracture SEM isithombe sesampula ye-NiTiHf DCT ngemuva kokushayela ukuhlolwa kokukhathala kokukhula ngaphansi komthwalo wokuchema ongaguquki ongu-250 N.
Kafushane, leli phepha lenza izivivinyo zokukhula kwe-crack yokukhathala komshini nokukhathala kuma-alloys enkumbulo yomumo we-nickel ecebile ye-NiTiHf okokuqala ngqa. Ngokusekelwe ekuhlanganisweni komjikelezo, isisho sokukhula sohlobo lwe-Paris somthetho wamandla siyaphakanyiswa ukuze silingane nezinga lokukhula kokukhathala lokuhlolwa ngakunye ngaphansi kwepharamitha eyodwa.
Isikhathi sokuthumela: Sep-07-2021