Alloys ebe nchekwa ihe (SMAs) nwere nzaghachi nrụrụ agwa maka mkpali temomechanical. Thermomechanical mkpali sitere na okpomọkụ dị elu, nchụpụ, mgbanwe siri ike na-esi ike, wdg (a na-akpọ usoro okpomọkụ dị elu dị elu austenite, na a na-akpọ obere okpomọkụ dị ala na-akpọ martensite). Mgbanwe nke usoro cyclic ugboro ugboro na-eduga n'ịbawanye nwayọọ nwayọọ na nkwụsịtụ, ya mere, ebe ndị na-adịghị agbanwe agbanwe ga-ebelata ọrụ nke SMA (nke a na-akpọ ike ọgwụgwụ ọrụ) ma mepụta microcracks, nke ga-emecha mee ka ọdịda anụ ahụ pụta mgbe ọnụọgụgụ buru ibu. N'ụzọ doro anya, ịghọta àgwà ndụ ike ọgwụgwụ nke alloys ndị a, dozie nsogbu nke mkpofu akụrụngwa dị oke ọnụ, na ibelata mmepe ihe na usoro mmepụta ngwaahịa ga-emepụta nnukwu nrụgide akụ na ụba.
Achọpụtabeghị ike ọgwụgwụ nke thermo-mechanical ruo n'ókè dị ukwuu, ọkachasị enweghị nyocha gbasara mgbasa mgbawa ike ọgwụgwụ n'okpuru okirikiri ọkụ-mechanical. Na mmalite mmejuputa SMA na biomedicine, ihe a na-elekwasị anya na nyocha ike ọgwụgwụ bụ ngụkọta ndụ nke ihe nlele "enweghị ntụpọ" n'okpuru ibu ọrụ cyclic. N'ime ngwa nwere obere geometry SMA, ike ọgwụgwụ na-eto eto anaghị enwe mmetụta dị nta na ndụ, yabụ nyocha ahụ na-elekwasị anya na igbochi mmalite mgbawa kama ịchịkwa uto ya; na ịnya ụgbọ ala, mbelata vibration na ike absorption ngwa, ọ dị mkpa iji nweta ike ngwa ngwa. Akụkụ SMA na-abụkarị nnukwu iji nọgide na-enwe mgbasa mgbape dị ịrịba ama tupu ọdịda. Ya mere, iji zute ihe ndị dị mkpa na ntụkwasị obi na nchekwa chọrọ, ọ dị mkpa ịghọta nke ọma na ịkọwapụta àgwà uto ike ọgwụgwụ site na usoro nkwụsị mmebi. Ngwa nke ụzọ nnabata mmebi nke na-adabere n'echiche nke igwe mgbaji na SMA adịghị mfe. E jiri ya tụnyere ọla nhazi ọdịnala, ịdị adị nke mgbanwe oge a na-emegharị emegharị na njikọ ọkụ na-arụ ọrụ na-ebute ihe ịma aka ọhụrụ iji kọwaa nke ọma ike ọgwụgwụ na oke mgbaji nke SMA.
Ndị nchọpụta si Texas A&M University dị na United States duziri dị ọcha n'ibu na chụpụrụ ike ọgwụgwụ mgbape ibu nnwale na Ni50.3Ti29.7Hf20 superalloy maka oge mbụ, na tụrụ aro ihe integral dabeere Paris-ụdị ike iwu okwu nke ike ga-eji maka Fit ike ọgwụgwụ. ọnụego mgbawa n'okpuru otu oke. A na-esi na nke a pụta na enwere ike ịkwado mmekọrịta siri ike na ọnụ ọgụgụ mgbape n'etiti ọnọdụ ntinye dị iche iche na nhazi geometric, nke enwere ike iji mee ihe dị ka onye nwere ike ịkọwapụta nrụrụ mgbawa na SMA. E bipụtara akwụkwọ ahụ metụtara ya na Acta Materialia nke nwere aha "Nkọwa jikọtara ọnụ nke nrụnye na ike ọgwụgwụ na-eto eto n'ụdị ebe nchekwa alloys".
Njikọ akwụkwọ:
https://doi.org/10.1016/j.actamat.2021.117155
Nnyocha ahụ chọpụtara na mgbe Ni50.3Ti29.7Hf20 alloy na-edobe ule uniaxial tensile na 180 ℃, austenite na-emeziwanye nke ọma n'okpuru ọkwa nrụgide dị ala n'oge usoro ntinye, na modul nke Young bụ ihe dịka 90GPa. Mgbe nrụgide ahụ ruru ihe dịka 300MPa Ná mmalite nke mgbanwe mgbanwe nke ọma, austenite na-agbanwe n'ime nrụgide na-akpata martensite; Mgbe a na-ebutu ya, martensite na-akpata nchekasị na-enwekarị nrụrụ na-agbanwe agbanwe, yana modul nke Young nke ihe dịka 60 GPa, wee gbanwee azụ na austenite. Site na mwekota, ike ọgwụgwụ na-eto eto nke ihe arụrụ arụ abanyela na nkwupụta iwu ike nke Paris.
Fig.1 BSE oyiyi nke Ni50.3Ti29.7Hf20 elu okpomọkụ udi ebe nchekwa alloy na size nkesa oxide ahụ.
Ọgụgụ 2 TEM oyiyi nke Ni50.3Ti29.7Hf20 elu okpomọkụ udi ebe nchekwa alloy mgbe okpomọkụ ọgwụgwọ na 550 ℃ × 3h
Fig. 3 Mmekọrịta dị n'etiti J na da/dN nke ike ọgwụgwụ n'ibu na-eto eto nke ụdị NiTiHf DCT na 180 ℃
Na nnwale na isiokwu a, e gosiri na a usoro nwere ike dabara ike ọgwụgwụ mgbape uto ọnụego data si niile nnwale na ike iji otu set nke parameters. Iwu ike exponent m bụ ihe dịka 2.2. Ntụle mgbawa ike ọgwụgwụ na-egosi na ma usoro mgbawa mgbawa na mgbasa nke ịnya ụgbọ ala bụ mgbaji na-agbaji agbaji, na ọnụnọ elu hafnium oxide na-anọkarị emewo ka mgbape mgbape ahụ dịkwuo njọ. Nsonaazụ enwetara na-egosi na otu okwu iwu iwu ike nwere ike nweta myirịta achọrọ n'ọtụtụ ọnọdụ nbudata na nhazi geometric, si otú a na-enye nkọwa dị n'otu nke ike ọgwụgwụ thermo-mechanical nke ụdị ebe nchekwa alloys, si otú ahụ na-atụle ike ịnya ụgbọ ala.
Fig. 4 SEM oyiyi nke mgbawa nke NiTiHf DCT ụdị mgbe 180 ℃ n'ibu ike ọgwụgwụ mgbawa ibu nnwale.
Ọgụgụ 5 Ọkpụkpụ SEM onyonyo nke NiTiHf DCT ụdị mgbe ịkwọchara ike ọgwụgwụ mgbawa uto uto n'okpuru oke nhụsianya mgbe niile nke 250 N.
Na nchịkọta, akwụkwọ a na-eduzi nnwale nleba anya n'ịgbawa n'ibu na ịnya ike ọgwụgwụ na nickel bara ụba na NiTiHf ebe nchekwa ọdịdị okpomọkụ dị elu maka oge mbụ. Dabere na cyclic mwekota, a Paris-ụdị ike-iwu mgbawa okwu uto na-atụ aro ka ọ dabara na ike ọgwụgwụ ọnụego uto nke ọ bụla nnwale n'okpuru otu oke oke.
Oge nzipu: Sep-07-2021