Tshiab tungsten alloys tau tsim nyob rau hauv Schuh Group ntawm MIT tuaj yeem hloov pauv cov uranium depleted hauv armor-piercing projectiles. Plaub xyoo cov ntaub ntawv science thiab engineering kawm tiav cov tub ntxhais kawm Zachary C. Cordero tab tom ua haujlwm ntawm cov tshuaj lom neeg tsawg, muaj zog, cov khoom siv high-density los hloov cov uranium depleted hauv kev siv tub rog. Depleted uranium ua rau muaj kev phom sij rau kev noj qab haus huv rau cov tub rog thiab cov pej xeem. Cordero hais tias "Qhov ntawd yog lub zog rau kev sim hloov nws," Cordero hais.

Ib txwm tungsten yuav nceb lossis blunt ntawm qhov cuam tshuam, qhov ua tau zoo tshaj plaws. Yog li qhov kev sib tw yog los tsim cov hlau uas tuaj yeem ua tau raws li qhov kev ua tau zoo ntawm cov uranium depleted, uas ua rau nws tus kheej-sharpening raws li nws txiav tawm cov khoom thiab tuav lub qhov ntswg ntse ntawm qhov nkag mus rau lub hom phiaj. "Tungsten los ntawm nws tus kheej yog tshwj xeeb muaj zog thiab nyuaj. Peb muab tso rau hauv lwm cov khoom sib xyaw ua kom nws thiaj li tuaj yeem sib sau ua ke rau hauv cov khoom loj no, "Cordero hais.

Ib qho tungsten alloy nrog chromium thiab hlau (W-7Cr-9Fe) muaj zog dua li kev lag luam tungsten alloys, Cordero tau tshaj tawm hauv ib daim ntawv nrog tus kws sau ntawv laus thiab Department of Materials Science thiab Engineering lub taub hau Christopher A. Schuh thiab cov npoj yaig hauv phau ntawv xov xwm Metallurgical thiab Materials Kev Lag Luam A. Kev txhim kho tau ua tiav los ntawm kev cog cov hmoov hlau hauv kev pabcuam sintering kub xovxwm, nrog rau qhov zoo tshaj plaws, ntsuas los ntawm cov qauv zoo thiab cov tawv tawv siab tshaj plaws, ua tiav ntawm lub sijhawm ua haujlwm ntawm 1 feeb ntawm 1,200 degrees Celsius. Lub sijhawm ua haujlwm ntev dua thiab kub siab dua ua rau cov nplej coarser thiab ua haujlwm tsis muaj zog. Co-sau suav nrog MIT engineering thiab cov ntaub ntawv kawm tiav cov tub ntxhais kawm Mansoo Park, Oak Ridge postdoctoral khub Emily L. Huskins, Boise State Associate Professor Megan Frary thiab cov tub ntxhais kawm tiav Steven Livers, thiab Army Research Laboratory mechanical engineer thiab pab pawg thawj coj Brian E. Schuster. Sub-scale ballistic xeem ntawm tungsten-chromium-hlau alloy kuj tau ua.

Cordero hais tias "Yog tias koj tuaj yeem ua tau nanostructured lossis amorphous bulk tungsten (alloy), nws yuav tsum yog cov khoom zoo tshaj plaws ballistic," Cordero hais. Cordero, ib haiv neeg ntawm Bridgewater, NJ, tau txais National Defense Science thiab Engineering (NDSEG) Kev Sib Raug Zoo hauv 2012 los ntawm Air Force Office of Scientific Research. Nws txoj kev tshawb fawb yog nyiaj txiag los ntawm US Defense Threat Reduction Agency.

Ultrafine grain qauv

"Txoj kev uas kuv ua kuv cov ntaub ntawv yog nrog cov hmoov ua thawj zaug peb ua nanocrystalline hmoov thiab tom qab ntawd peb sib sau ua ke rau hauv ib qho khoom loj. Tab sis qhov kev sib tw yog tias kev sib sau ua ke yuav tsum nthuav tawm cov khoom kom kub siab dua, "Cordero hais. Cua sov cov alloys mus rau qhov kub thiab txias yuav ua rau cov nplej, los yog ib tug neeg crystalline domains, nyob rau hauv cov hlau kom loj, uas ua rau lawv tsis muaj zog. Cordero muaj peev xwm ua tiav cov qauv nplej ultrafine txog li 130 nanometers hauv W-7Cr-9Fe compact, paub tseeb los ntawm electron micrographs. "Siv txoj kev ua cov hmoov no, peb tuaj yeem ua cov qauv loj txog li 2 centimeters nyob rau hauv txoj kab uas hla, los yog peb tuaj yeem loj dua, nrog lub zog compressive zog ntawm 4 GPa (gigapascals). Qhov tseeb tias peb tuaj yeem ua cov ntaub ntawv no siv cov txheej txheem scalable yog tej zaum qhov zoo tshaj plaws, "Cordero hais.

"Dab tsi peb tab tom sim ua raws li ib pab pawg yog ua ntau yam nrog cov nanostructures zoo. Yog vim li cas peb xav tau qhov ntawd yog vim tias cov ntaub ntawv no muaj cov khoom nthuav dav uas muaj peev xwm siv tau hauv ntau daim ntawv thov, "Cordero ntxiv.

Tsis pom nyob rau hauv qhov

Cordero kuj tau tshuaj xyuas lub zog ntawm cov hlau alloy hmoov nrog nanoscale microstructures nyob rau hauv ib phau ntawv xov xwm Acta Materialia. Cordero, nrog tus kws sau ntawv laus Schuh, tau siv ob qho kev sim simulations thiab kev sim tshuaj ntsuam xyuas kom pom tias cov hlau alloys xws li tungsten thiab chromium nrog lub zog pib zoo sib xws tau ua kom homogenize thiab tsim cov khoom muaj zog kawg, qhov sib txuas ntawm cov hlau nrog lub zog pib loj tsis sib haum xws li. raws li tungsten thiab zirconium tended los tsim ib tug tsis muaj zog alloy nrog ntau tshaj ib theem tam sim no.

"Cov txheej txheem ntawm lub zog siab pob milling yog ib qho piv txwv ntawm tsev neeg loj ntawm cov txheej txheem uas koj deform lub heck tawm ntawm cov ntaub ntawv los tsav nws cov microstructure mus rau hauv lub weird non-equilibrium xeev. Tsis muaj lub moj khaum zoo tiag tiag rau kev kwv yees lub microstructure uas tawm los, yog li ntau zaus qhov no yog qhov kev sim thiab yuam kev. Peb tau sim tshem tawm qhov kev pom zoo los ntawm kev tsim cov alloys uas yuav tsim cov tshuaj metastable, uas yog ib qho piv txwv ntawm theem tsis sib npaug, "Cordero piav qhia.

"Koj tsim cov theem tsis sib npaug, yam uas koj yuav tsis nquag pom hauv ntiaj teb ib puag ncig koj, hauv qhov xwm txheej, siv cov txheej txheem deformation tiag tiag," nws hais. Cov txheej txheem ntawm high-zog pob zeb milling yuav tsum rov shearing ntawm cov hmoov hlau nrog lub shearing tsav lub alloying ntsiab rau intermix thaum sib tw, thermally-activated rov qab txheej txheem tso cai rau cov hlau rov qab mus rau nws equilibrium xeev, uas nyob rau hauv ntau rooj plaub yog mus rau theem sib cais. . "Yog li muaj kev sib tw ntawm ob txoj haujlwm no," Cordero piav qhia. Nws daim ntawv thov tus qauv yooj yim los kwv yees chemistry nyob rau hauv ib qho kev muab alloy uas yuav tsim ib qho kev daws teeb meem thiab siv tau nrog kev sim. Cordero hais tias, "Cov hmoov zoo li-milled yog qee cov hlau nyuaj tshaj plaws uas tib neeg tau pom," Cordero hais tias, cov kev ntsuam xyuas pom tau tias cov tungsten-chromium alloy muaj qhov nyuaj ntawm nanoindentation ntawm 21 GPa. Qhov ntawd ua rau lawv txog ob npaug ntawm nanoindentation hardness ntawm nanocrystalline hlau-raws li alloys los yog coarse-grained tungsten.

Metallurgy xav tau yooj yim

Nyob rau hauv ultrafine grain tungsten-chromium-hlau alloy compacts nws kawm, cov alloys khaws cov hlau los ntawm kev puas tsuaj ntawm steel sib tsoo xov xwm thiab vial thaum lub sij hawm high-zog pob milling. "Tab sis nws hloov tawm tias tseem tuaj yeem yog qhov zoo, vim nws zoo li nws ua kom nrawm nrawm ntawm qhov kub thiab txias, uas txo cov sij hawm koj yuav tsum tau siv ntawm qhov kub siab uas tuaj yeem ua rau muaj kev hloov pauv tsis zoo hauv microstructure," Cordero piav qhia. "Qhov loj tshaj plaws yog hloov tau thiab lees paub cov hauv kev hauv metallurgy."

Lub compacted hlau alloy pellet zaum ib sab ntawm li-milled tungsten-chromium hlau hlau hmoov nyob rau hauv ib lub nkoj siv rau hnyav cov hlau. Cov pob steel yog siv los deform cov hlau nyob rau hauv lub zog siab pob zeb. Credit: Denis Paiste/Materials Processing Center
Cordero kawm tiav los ntawm MIT hauv 2010 nrog bachelor's hauv physics thiab ua haujlwm rau ib xyoos ntawm Lawrence Berkeley National Lab. Nyob ntawd, nws tau txais kev tshoov siab los ntawm cov neeg ua haujlwm engineering uas tau kawm los ntawm ib tiam dhau los ntawm metallurgists uas tau tsim tshwj xeeb crucibles los tuav plutonium rau Manhattan Project thaum Ntiaj Teb Tsov Rog II. "Hnov cov khoom uas lawv tau ua haujlwm ua rau kuv zoo siab heev thiab mob siab rau kev ua cov hlau. Nws kuj tsuas yog lom zem heev, "Cordero hais. Hauv lwm cov ntaub ntawv kev kawm txuj ci, nws hais tias, "Koj tsis tuaj yeem qhib lub qhov cub ntawm 1,000 C, thiab pom ib yam dab tsi ci liab kub. Koj tsis tau txais cov khoom kho cua sov. " Nws cia siab tias yuav ua tiav nws PhD hauv 2015.

Txawm hais tias nws txoj haujlwm tam sim no tau tsom mus rau kev siv cov txheej txheem, hom kev ua cov hmoov nplej uas nws ua kuj tseem siv los ua cov khoom sib nqus. "Ntau cov ntaub ntawv thiab kev paub tuaj yeem siv rau lwm yam," nws hais. "Txawm hais tias qhov no yog ib txwm siv cov txheej txheem metallurgy, koj tuaj yeem siv cov qub tsev kawm ntawv metallurgy rau cov ntaub ntawv tshiab hauv tsev kawm ntawv."