Investigation on the Thermal Behavior, Mechanical Properties and Reaction Characteristics of Al-PTFE Composites Enhanced by Ni Particle

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1 mterils Article Investigtion on rml Behvior, Mechnicl Properties Rection Chrcteristics Al-PTFE Composites Enhnced by Ni Prticle Jixing Wu 1, Huixi Wng 2, Xing Fng 1, Yuchun Li 1, *, Yiming Mo 1, Li Yng 1, Qin Yin 1, Shungzhng Wu 1, Mio Yo 1 Jixing Song 1 1 College Field Engineering, PLA Army Engineering University, Nnjing , Chin; wujixing1356@163.com (J.W.); fngxing3579@163.com (X.F.); liyuchunmil@163.com (Y.M.); speedinessli@163.com (L.Y.); dfyq1982@21.com (Q.Y.); wushzh4394@126.com (S.W.); yoshunmio@126.com (M.Y.); @163.com (J.S.) Troop PLA, Nnjing , Chin; whx @163.com * Correspondence: liyuchunmil@163.com; Tel.: Received: 1 September 2018; Accepted: 14 September 2018; Published: 16 September 2018 Abstrct: Al-PTFE (luminum-polytetrfluoroene) is regrded s one most promising rective mterils (RMs). In this work, Ni (Nickel) dded Al-PTFE composites for purpose improving energy density dmge effect. To investigte rml behvior, mechnicl properties rection chrcteristics composites, n Al-PTFE mixture n Al-Ni mixture prepred by ultrsonic mixing. Six types different component mss rtios prepred by molding sintering. Simultneous rml nlysis experiments crried out chrcterize rml behvior Al-PTFE mixture Al-Ni mixture. Qusi-sttic tests performed nlyze mechnicl properties rection chrcteristics. results indicte tht rection onset temperture Al-Ni (582.7 C) similr tht Al-PTFE (587.6 C) tht rection het Al-Ni (991.9 J/g) 12.5 times higher thn tht Al-PTFE (79.6 J/g). With increse Ni content, mteril chnged from ductile brittle strin hrdening modulus compressive strength rose first n subsequently decresed, reching mximum MP MP respectively when volume frction Ni 10%. An exormic rection occurred for Ni volume frction no more thn 10% under, ccompnied by formtion Ni-Al intermetllic compounds. In system, rection between Al PTFE preceded rection between Al Ni fesibility incresing energy density dmge effect rective mteril by mens Ni-Al rection proved. Keywords: ; rml behvior; mechnicl properties; rection chrcteristics; DSC; 1. Introduction Rective mterils, which re generlly composed two or more non-explosive solid mterils, re new type energetic mteril induced by n impct. y sty inert under norml temperture pressure undergo violent rection under impct while generting new substnces relesing lrge mount het [1 3]. As typicl rection mteril, Al-PTFE (luminum-polytetrfluoroene) hs chrcteristics higher energy density, better mechnicl properties, stronger stbility, esier preprtion compred trditionl energetic mterils such s explosives propellnts [4,5]. In this regrd, it hs gret ppliction vlue development Mterils 2018, 11, 1741; doi: /m

2 Mterils 2018, 11, prospects in militry. It cn be mde in high-energy wrhed n impct-rection secondry dmge in form n energetic liner or rection frgment while penetrting trget by its own kinetic energy. Chemicl rections such s explosions combustion will be triggered so s chieve dmge trget [6,7]. Wher Al-PTFE rective mteril cn obtin good ppliction depends on if it hs sufficient strength ensure its sfety under conditions production, ing, srge explosive loding chemicl rection cn occur when penetrting trget. refore, in order improve strength density mterils, experimentl reserch hs been conducted worldwide primrily focus on engineering strin Al-PTFE under different influence fcrs performnce chnge fter dding different fillers. Feng found tht n Al-PTFE specimen, through specil het tretment, could rect violently under for first time on this bsis, effects sintering temperture, mteril rtio, Al prticle size on rection Al-PTFE scertined [8,9]. Wu studied impct exerted by Al prticle size on mechnicl properties rection chrcteristics Al-PTFE. It found tht increse in Al prticle size, strength sensitivity mteril decresed ctivtion rection Al PTFE becme more more difficult occur. formtion circumferentil open crcks prerequisite for Al-PTFE undergo rective rection [10]. Ci investigted mechnicl properties Al-W-PTFE mterils found tht ddition W prticles could effectively improve strength Al-PTFE [11]. Herbold studied effect W prticle size on strength, filure shock behvior Al-W-PTFE composites by mens experimenttion simultion. results indicted tht strength Al-W-PTFE incresed decrese in W prticle size [12]. Yu conducted experiments discovered tht ddition TiH2 prticles Al-PTFE cn significntly enhnce strength composite specil flme, different from Al-PTFE rection, observed in rection phenomenon [13]. previous reserch minly focused on performnce chnge Al-PTFE dded W prticles re is little reserch on performnce chnge fter dding Ni prticles [14 16]. Although W hs n extremely high density (19.3 g/cm 3 ), since W does not prticipte in rection, it is only used s crrier for mss ddition Al-PTFE energy density mteril is inevitbly lod under condition tht volume frction mteril is constnt. Ni hs higher density (8.9 g/cm 3 ) Ekins found tht Ni Al cn undergo chemicl rections under impct loding form Ni-Al intermetllic compounds [17 19]. In this regrd, ddition Ni prticles Al-PTFE not only cn increse strength density mteril but cn lso increse energy density mteril enhnce dmging effect on trget. In this pper, rml behvior n Al-PTFE mixture n Al-Ni mixture chrcterized by rmogrvimetric-differentil scnning clorimetry (TG-DSC) six types different equivlence rtios prepred. ir mechnicl properties rection chrcteristics under investigted. 2. Experimentl Section 2.1. Mterils initil powders dopted crry out experiments following verge size: PTFE: 25 µm (from 3M, Shnghi, Chin); Al: 1 2 µm (from JT, Hunn, Chin); Ni: 2 µm (from Niou, Shnghi, Chin) Specimen Preprtion For rml nlysis, mss rtios between Al PTFE set 26.5%/73.6% ( chemicl equilibrium rtio) Al Ni mixed ccording mss rtio 31%:69% (mole rtio 1:1) using ultrsonic mixing method. Two kinds mixtures sonicted for 30 min in sonic bth prepre homogeneously dispersed solution n dried in vcuum oven for 24 h t 60 C.

3 Mterils 2018, 11, Mterils 2018, 11, x FOR PEER REVIEW 3 10 For For,, six six types types different different equivlence equivlence rtios rtios prepred. prepred. Tble Tble 1 lists lists equivlence equivlence rtio rtio oreticl oreticl mximum mximum density density (TMD) (TMD) for for six six types types ; ; type type A specimen specimen (Al/Ni/PTFE: (Al/Ni/PTFE: vol vol %/0/78 %/0/78 vol %) vol %) prepred prepred serve serve s s reference. reference. preprtion preprtion included included mixing, mixing, cold cold isosttic isosttic pressing pressing vcuum vcuum sintering, sintering, which which bsed bsed on on ptent ptent Nielson [20]. Nielson procedure [20]. procedure s follows: s follows: Al-PTFE mixture Al-PTFE mixture stirred using stirred mor-driven using mor-driven blender for 20 blender min in n for ethnol 20 min solution, in n ethnol n solution, put in n vcuum put in drying vcuum oven for drying 48 h t oven 60 for C 48 h cold t 60 pressed C in cold cylinders pressed in sizes cylinders Φ10 mm sizes 10 mm Φ10 under mm compressive 10 mm under pressure compressive 300 MP. pressure Finlly, 300 pressed MP. Finlly, pressed heted in vcuum heted oven t in vcuum sintering oven temperture t sintering 360 temperture C for 4 h 360 heting C for 4 rte h 90 heting C h 1 rte cooling 90 C h rte 1 50 cooling C h 1. rte temperture 50 C h 1. hisry temperture sintering hisry cycle is depicted sintering in Figure cycle is 1. depicted in Figure 1. Tble Tble equivlence equivlence rtios rtios TMD TMD (oreticl (oreticl mximum mximum density) density) six six types types.. Volume Frction (vol %) Mss Frction (wt %) Type Volume Frction (vol %) Mss Frction (wt %) TMD TMD (g/cm (g/cm 3 ) 3 ) Al Ni PTFE Al Ni PTFE Al Ni PTFE Al Ni PTFE A 22% 0 78% 26.5% % 2.31 A 22% 0 78% 26.5% % 2.31 B 22% 5% 73% 22.8% 17.1% 60.2% % 5% 73% 22.8% 17.1% 60.2% 2.61 C 22% 22% 10% 10% 68% 68% 20.2% 30.2% 30.2% 49.6% 49.6% D 22% 20% 20% 58% 16.4% 49.2% 34.4% 3.62 E 22% 30% 30% 48% 13.8% 62.2% 24.0% 4.30 F 22% 22% 40% 40% 38% 38% 11.9% 71.6% 71.6% 16.4% 16.4% Experimentl Experimentl Procedures Procedures Figure 1. temperture hisry sintering cycle. An An investigtion investigtion in in rml rml behvior behvior crried crried out using out using TG/DSC TG/DSC simultneous simultneous rml nlyzer. rml nlyzer. verge smple verge mss smple bout mss 2.0 mg bout 2.0 mg heting rte heting 5 C/min, rte covering 5 C/min, tempertures covering tempertures from from C. 20 Argon 1000 C. used Argon s insured used s gs insured flow gs rte 30 flow ml/min. rte 30 ml/min. Qusi-sttic tests performed using universl mterils testing mchine (CMT5105, Qusi-sttic MTS, Eden Pririe, MN, tests USA) performed mximum using loding universl cpcity mterils 100 testing kn. A lod mchine pplied (CMT5105, t MTS, speed Eden 6 mm min Pririe, 1 MN, corresponding USA) mximum nominl loding strin rte cpcity 0.01 s Prior kn. A lod tests, both pplied ends t speed specimen 6 mm min 1 lubricted corresponding petroleum nominl jelly strin iming rte 0.01 llevite s 1. Prior impct tests, friction. both ends Ech type specimen lubricted tested three times petroleum for jelly ske iming gurnteeing llevite relibility impct friction. experimentl Ech type results. To observe tested rection three times for six types ske gurnteeing under relibility experimentl more results. ccurtely, To observe time sequences rection rection six types cptured using under high-speed cmer (FASTCAM more ccurtely, SA-Z, Photron, time Tokyo, sequences Jpn) rection frme rte up cptured 10,000 frmes/s. using In high-speed ddition, cmer residues (FASTCAM SA-Z, Photron, fter Tokyo, Jpn) frme rte chrcterized up 10,000 by frmes/s. In ddition, residues fter

4 DSC curves for Al-PTFE Al-Ni mixtures re presented in Figure 4 ll rml nlyses re summrized in Tble 2. As cn be seen from Figure 4, re three endormic peks one exormic pek in Figure 4. endo-pek-a strted t C TG curve showed no mss chnge. It cn be obtined tht endo-pek-a melting endormic pek Mterils 2018, 11, Mterils 2018, 11, x FOR PEER REVIEW 4 10 X-ry chrcterized diffrction by (Bruker X-ry diffrction D8 ADVANCE, (Bruker Bruker, D8 ADVANCE, Berlin, Germny). Bruker, Berlin, A S-3400N Germny). II scnning A S-3400N electron II scnning microscope electron (SEM) microscope (Hitchi, Tokyo, (SEM) Jpn) (Hitchi, Tokyo, used Jpn) observe used interior observe microstructures interior microstructures before before. Figure. 2 showsfigure smples 2 shows used smples for DSCused for DSC.. Figure 2. smples used for DSC (differentil scnning clorimetry) : () Al-PTFE (luminum-polytetrfluoroene) mixture used used for for DSC; DSC; (b) (b) Al-Ni Al-Ni mixture mixture used used for DSC; for DSC; (c) (c) specimen specimen used for used for.. 3. Results Discussion 3.1. Mesoscle Chrcteristics 3.1. Mesoscle Chrcteristics interior microstructures re shown in Figure 3. Figure 3,b compre interior microstructures re shown in Figure 3. Figure 3,b compre locl interior microstructurl chrcteristics type A specimen before sintering fter sintering locl interior microstructurl chrcteristics type A specimen before sintering fter in cse sme mgnifiction. Plinly, re crowd voids pores existing between sintering in cse sme mgnifiction. Plinly, re crowd voids pores Al prticles PTFE mtrix before sintering. On contrry, it distinctly observed existing between Al prticles PTFE mtrix before sintering. On contrry, it tht Al prticles embedded in PTFE mtrix very tightly out voids fter sintering, distinctly observed tht Al prticles embedded in PTFE mtrix very tightly out s shown in Figure 3b. In this regrd, min function sintering obtin cross-linking voids fter sintering, s shown in Figure 3b. In this regrd, min function sintering polymeric mteril permit prticles fuse ger form homogeneous mteril. obtin cross-linking polymeric mteril permit prticles fuse ger form After sintering, mechnicl properties specimen significntly improved by virtue homogeneous mteril. After sintering, mechnicl properties specimen significntly Mterils recrystlliztion improved 2018, by 11, virtue x FOR PTFE. PEER REVIEW recrystlliztion PTFE Figure 3c f illustrtes overll interior microstructurl chrcteristics type A, B, C F fter sintering. Al Ni cn be discriminted fcilely from PTFE mtrix due ir sphericl geometry. It observed tht Al, Ni PTFE powders hve been homogeneously mixed through preprtion used in this pper. With increse in Ni content, color SEM imges becme deeper owing Ni prticles s brighter fetures compred Al prticles rising from lower mic number. As cn be seen from Figure 3c e, when content Ni reltively low, Al Ni well embedded in PTFE mtrix plyed role supporting mtrix. However, excessive Ni destroyed continuity PTFE mtrix, which cn be observed in Figure 3f. Figure 3. interior microstructures : () type A specimen before sintering; (b) type A specimen fter fter sintering (locl); (locl); (c) (c) type type A specimen A specimen fter fter sintering sintering (overll); (overll); (d) (d) type B type specimen B specimen fter sintering; fter sintering; (e) type (e) C specimen type C specimen fter sintering; fter sintering; (f) type (f) F specimen type F specimen fter sintering. fter sintering rml Behvior Al-PTFE Al-Ni Mixtures

5 Mterils 2018, 11, Figure 3c f illustrtes overll interior microstructurl chrcteristics type A, B, C F fter sintering. Al Ni cn be discriminted fcilely from PTFE mtrix due ir sphericl geometry. It observed tht Al, Ni PTFE powders hve been homogeneously mixed through preprtion used in this pper. With increse in Ni content, color SEM imges becme deeper owing Ni prticles s brighter fetures compred Al prticles rising from lower mic number. As cn be seen from Figure 3c e, when content Ni reltively low, Al Ni well embedded in PTFE mtrix plyed role supporting mtrix. However, excessive Ni destroyed continuity PTFE mtrix, which cn be observed in Figure 3f rml Behvior Al-PTFE Al-Ni Mixtures DSC curves for Al-PTFE Al-Ni mixtures re presented in Figure 4 ll rml nlyses re summrized in Tble 2. As cn be seen from Figure 4, re three endormic peks one exormic pek in Figure 4. endo-pek-a strted t C TG curve showed no mss chnge. It cn be obtined tht endo-pek-a melting endormic pek PTFE. endo-pek-b strted t C, ccompnied by decrese in smple qulity, indicting formtion gses, which cn be judged s decomposition PTFE. exo-pek-c begn t C judged be n exormic rection between Al decomposition product PTFE; rection het 79.6 J/g. endo-pek-d strted t bout C, which melting endormic pek incompletely rected Al powder smple qulity did not chnge during this period. According Figure 4b, it cn be seen tht re only one exormic pek in during whole heting, implying tht re rection between Al Ni strting t C tht re no residul Al powder, orwise re would hve been n endormic pek for Al powder melting t bout 660 C. In cse sme heting rte, rection het Al-Ni J/g, which 12.5 times higher thn tht Al-PTFE. No. Tble 2. prmeters for endormic exormic peks in DSC curves. Onset Temperture/( C) Pek Temperture/( C) End Temperture/( C) Het Relese/(J/g) Endo-pek-A Endo-pek-B Exo-pek-C Endo-pek-D Exo-pek-E Mterils 2018, 11, x FOR PEER REVIEW Figure 4. TG-DSCcurves curves for for Al-PTFE Al-PTFE Al-Ni Al-Ni mixtures: mixtures: () () Al-PTFE Al-PTFE mixture; mixture; (b) (b) Al-Ni mixture. Al-Ni mixture Mechnicl Properties under Qusi-Sttic Compression Tke experimentl results type A specimen, for exmple, true stress-strin curves obtined by triplicte experiments lmost overlpped ger ok on high degree greement s shown in Figure 5, which implied tht testing dt good consistency.

6 Mterils Figure 2018, 4. 11, 1741TG-DSC curves for Al-PTFE Al-Ni mixtures: () Al-PTFE mixture; (b) 6 10 Al-Ni mixture Mechnicl Properties under Qusi-Sttic Compression Tke experimentl results type A specimen, for exmple, true stress-strin curves obtined by by triplicte experiments experiments lmost lmost overlpped overlpped ger ger ok onok high on degree high greement degree s greement shown ins Figure shown 5, in which Figure implied 5, which tht implied testing tht dt testing dt good consistency. good consistency. Figure 5. true stress-strin curves for type A specimen from triplicte experiments. Figure 6 sketches true true stress-strin curves curves for for six types six types under under.. As shown As shown in Figure in Figure 6, 6, six six types ll experienced liner elstic stge under elstic moduli similr. This phenomenon owing fct tht elstic deformtion minly crried out by morphous st prt PTFE mtrix, which minly represented by by interlmellr slip slip in in morphous region region this this reversible [21]. [21]. However, difference is tht is tht when when Ni volume Ni volume frction frction less thn less 30%, thn 30%, (type A, (type B, C, D) A, went B, C, through D) went n elstic through deformtion n elstic deformtion plstic deformtion plstic during deformtion during strin hrdening occurred strin hrdening fter yielding; occurred yet when fter yielding; Ni volume yet when frction Ni greter volume thn frction 30%, greter thn (type 30%, E, F) only underwent (type liner E, F) elstic only stge underwent filure liner stge elstic stge filed directly filure fter stge reching filed yielddirectly strength. fter This reching is becuse yield Ni filler strength. plyed This nis importnt becuse role Ni infiller reinforcing plyed importnt mterilsrole when in reinforcing Ni content mterils low. However, when excessive Ni content Ni would low. destroy However, continuity excessive Ni would PTFE mtrix, destroy leding continuity reduction PTFE mteril s mtrix, Mterils strength, leding 2018, which 11, reduction x cn FOR be PEER confirmed REVIEW mteril s in type strength, F in which Figurecn 6. be confirmed in type F in Figure Figure true true stress-strin stress-strin curves curves for for six types six types under under.. mechnicl property prmeters six types, clculted bsed on stress-strin dt, re illustrted in Tble 3. As Tble 3 lists, ddition Ni prticles Al-PTFE hd significnt effect on mechnicl properties mteril. As Ni content rose, strength mteril first incresed subsequently decresed. When Ni volume frction 10%, strin hrdening modulus compressive strength (which represents strength

7 Mterils 2018, 11, mechnicl property prmeters six types, clculted bsed on stress-strin dt, re illustrted in Tble 3. As Tble 3 lists, ddition Ni prticles Al-PTFE hd significnt effect on mechnicl properties mteril. As Ni content rose, strength mteril first incresed subsequently decresed. When Ni volume frction 10%, strin hrdening modulus compressive strength (which represents strength mteril reched t mximum) which MP MP respectively. Besides, filure strin mteril decresed mononously increse in Ni content, reching mximum vlue 2.04 when mteril not dded Ni minimum vlue 0.35 when Ni volume frction 40%, indicting tht mteril chnged from ductile brittle n incresing Ni content. Tble 3. Mechnicl properties six types under. Type Yield Strength/MP Elstic Modulus/MP Hrdening Modulus/MP Compressive Strength/MP Filure Strin A B C D E F Rection Chrcteristics under Qusi-Sttic Compression In test, it observed tht type A, B, C underwent violent rection ll rected completely, wheres no rection occurred in type D, E, F. rection type A, B, C, cptured using high-speed cmer, re shown in Figure 7. As Figure 7 indictes, ignition phenomenon type C specimen turned out be most intense mong three. In contrst, rection intensity type A specimen slightly weker thn tht type B C. Aprt from this, rection time type C specimen shortest (~500 ms), which little higher thn tht type A (~620 ms) B (~720 ms). conclusion tht cn be reched is tht dding Ni Al-PTFE cn enhnce rection intensity rection speed mteril under pre-requisite tht Mterils 2018, Ni volume 11, x FOR frction PEER REVIEW is not more thn 10% Figure 7. Rection type A, A, B, B, C under : () () type type A specimen; A (b) (b) type type B specimen; B (c) (c) type type C specimen. C To To explin explin experimentl experimentl phenomenon phenomenon in in underst underst chemicl chemicl rection rection mechnism mechnism,, residues residues chrcterized chrcterized by by X-ry X-ry diffrction. diffrction. X-ry X-ry diffrction diffrction results results for for rection rection residues residues type type C specimen specimen fter fter re presented in Figure 8. results show tht AlF3, Ni3Al, NiAl produced during rection type C specimen. On this bsis, chemicl rection under cn be concluded s follows: ( ) 4Al+3 -C F - 4AlF + 6C 2 4 3

8 he X-ry diffrction results for rection residues type C specimen fter qusi-stti ompression re presented in Figure 8. results show tht AlF3, Ni3Al, NiAl produce uring rection type C specimen. On this bsis, chemic ection Mterils 2018, 11, 1741 under cn be concluded s 8 follows: 10 ( ) 4Al+3 -C F - 4AlF + 6C + re presented in Figure 8. 2 results 4 show tht3alf 3, Ni 3 Al, NiAl produced during rection type C specimen. On this bsis, chemicl rection Al under3ni Ni 3Al cn be concluded s follows: Al 4Al + Ni + 3( C 2 NiAl F 4 ) 4AlF 3 + 6C Al + 3Ni Ni 3 Al. (1) Al + Ni NiAl. (1) Arising from bsence Al Ni in residues, it cn be obtined tht Al Ni h ected completely. Besides, re no NiF2 in resultnt residue, indicting tht re n ection between Ni PTFE. Arising from bsence Al Ni in residues, it cn be obtined tht Al Ni hd rected completely. Besides, re no NiF 2 in resultnt residue, indicting tht re no rection between Ni PTFE. Figure 8. X-ry diffrction result rection residues type C specimen fter. Figure 8. X-ry diffrction result rection residues type C specimen fter. Feng put forwrd crck-induced initition mechnism fter he found tht Al-PTFE underwent violent rection under. A simple description is tht when stress reches Feng put forwrd compressive crck-induced strength Al-PTFE initition specimen, mechnism crck tip fter genertes he locl found hot spots tht instntly Al-PTFE underwen violent rection stimulting under specimen rect [9].. By compring rml A simple behvior description mechnicl is properties tht when stres mterils, nlyzing rection phenomen in test, linking eches compressive strength Al-PTFE specimen, crck tip genertes locl hot spot crck-induced initition mechnism, following conclusions cn be drwn. On one h, for nstntly stimulting type A, B, C, which cn rect rect [9]. under By compring, rml by virtuebehvior ir higher mechnic roperties strength mterils, better nlyzing ughness, rection phenomen could bsorb more in energy during test, n hot spots crck tip could stimulte rection Al PTFE. energy inking crck-induced initition mechnism, following conclusions cn be drwn. On on relesed by rection furr excited rection Al Ni. According nlysis, for type A, B, C, which cn rect under, by virtue o rml behvior, rection het Al-Ni fr higher thn tht Al-PTFE under sme volume frction. refore, rection type C specimen more violent thn tht type A specimen. This furr proves fesibility incresing energy density dmge effect rective mteril by mens Ni-Al rection. On or h, type D, E, F not cpble recting under. Due high content Ni, mteril becme brittle ughness reltively low. mteril filed directly fter compressive strength reched energy bsorbed insufficient generte locl hot spots t crck tip. refore, Al PTFE not cpble recting rection between Al Ni did not occur becuse lck excittion rection energy Al PTFE.

9 Mterils 2018, 11, Conclusions In this pper, rml behvior Al-PTFE n Al-Ni mixture studied using DSC method. mechnicl properties rection chrcteristics six types under scertined. conclusions cn be drwn s follows: (1) TG-DSC curves Al-PTFE Al-Ni mixtures illustrted tht rection between Al PTFE begn t C, rection between Al Ni strted t C, rection het Al-Ni (991.9 J/g) 12.5 times higher thn tht Al-PTFE (79.6 J/g). (2) ddition Ni prticles Al-PTFE hd significnt effect on mechnicl properties mteril. With increse in Ni content, mteril chnged from ductile brittle strin hrdening modulus compressive strength rose first subsequently decresed, reching mximum MP MP respectively when Ni volume frction 10%. (3) In test, no rection occurred for Ni volume frction 20, 30 40%, while n exormic rection occurred for Ni volume frction 0, 5 10%. As rection het Al-Ni fr higher thn tht Al-PTFE, rection intensity rection speed ok on n upwrd trend s Ni content incresed. (4) In system, rection between Al PTFE preceded rection between Al Ni fesibility incresing energy density dmging effect rective mteril by mens Ni-Al rection proved. Author Contributions: X.F. Y.L. conceived designed experiments; J.W., H.W., Q.Y. J.S. performed experiments; Y.M., L.Y., S.W. M.Y. nlyzed dt; J.W. wrote pper. Funding: This reserch funded by Ntionl Nturl Science Foundtion Chin (No ) Ntionl Science Fund for Distinguished Young Scholrs (No ). Acknowledgments: finncil support from Ntionl Nturl Science Foundtion Chin (Generl Progrm. Grnt No ) Ntionl Science Fund for Distinguished Young Scholrs (project No ) re grtefully cknowledged. Conflicts Interest: uthors declre no conflicts interest. References 1. Nielson, D.B.; Truitt, R.M.; Ashcrt, B.N. Rective Mteril Enhnced Projectiles Relted Methods. U.S. Ptent , 20 Ocber Hunt, E.M.; Mlcolm, S.; Pny, M.L.; Dvis, F. Impct ignition nno micron composite energetic mterils. Int. J. Impct Eng. 2009, 36, [CrossRef] 3. Mock, W., Jr.; Holt, W.H. Impct Initition Rods Pressed Polytetrfluoroethylene (PTFE) Aluminum Powders. In Proceedings AIP Conference Proceedings, Albuquerque, NM, USA, Februry 2006; Americn Institute Physics: College Prk, MD, USA, 2006; Volume 845, pp Zhng, X.F.; Shi, A.S.; Qio, L.; Zhng, J.; Zhng, Y.G.; Gun, Z.W. Experimentl study on impct-initited chrcters multifunctionl energetic structurl mterils. J. Appl. Phys. 2013, 113, [CrossRef] 5. Glvier, L.; Tn, G.; Ducéré, J.-M.; Bijot, V.; Pinon, S.; Clis, T.; Estève, A.; Rouhni, M.D.; Rossi, C. Nnoenergetics s pressure generr for nonxic impct primers: Comprison Al/Bi 2 O 3, Al/CuO, Al/MoO 3 nnormites Al/PTFE. Combust. Flme 2015, 162, [CrossRef] 6. Wng, H.; Zheng, Y.; Yu, Q.; Liu, Z.; Yu, W. Impct-induced initition energy relese behvior rective mterils. J. Appl. Phys. 2011, 110, Sorensen, B. High-velocity impct encsed Al/PTFE projectiles on structurl Aluminum rmor. Procedi Eng. 2015, 103, [CrossRef] 8. Feng, B.; Fng, X.; Li, Y.C.; Wng, H.X.; Mo, Y.M.; Wu, S.Z. An initition phenomenon Al-PTFE under. Chem. Phys. Lett. 2015, 637, [CrossRef]

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