亞穩(wěn)β鈦合金有比強度高、深淬透性好和冷熱成型性能優(yōu)良等特點,在航空航天、海洋工程、軌道交通等領(lǐng)域有廣闊的應(yīng)用前景[1~5]
這類合金??捎糜谥圃熵撦d的結(jié)構(gòu)件,因此對其強度和塑性等力學(xué)性能的要求很高
亞穩(wěn)β鈦合金的組織對熱處理十分敏感,熱處理對β基體內(nèi)析出次生α相的形貌、尺寸、分布和體積分數(shù)有顯著的影響,使其強度和塑性不同[6]
因此,熱處理可在較大區(qū)間內(nèi)調(diào)整這類合金的強度和塑性[7~9]
關(guān)于熱處理后亞穩(wěn)β鈦合金的組織、強度和塑性,已經(jīng)有大量的研究工作[10]
Li等[11]發(fā)現(xiàn),經(jīng)過850℃/1 h固溶處理和500℃/2 h單級時效處理的Ti-2Al-9.2Mo-2Fe合金強度最高,其抗拉強度為1543 MPa,達到了超高強鈦合金標(biāo)準
Zheng等[12]的研究發(fā)現(xiàn),固溶+雙級時效處理也能大幅度提高亞穩(wěn)β鈦合金的強度
在預(yù)時效階段析出的ω相在二次時效階段促進次生α相形核,進而生成更加細小彌散且分布均勻的次生α相,從而使合金的強度提高
馬權(quán)等[13]對TB8合金進行固溶+雙級時效處理后發(fā)現(xiàn),次生α相明顯細化使合金抗拉強度的提高超過了17%
Zhou等[14]則發(fā)現(xiàn),與其他熱處理工藝相對,固溶+隨爐冷卻處理也能顯著提高合金的力學(xué)性能,生成枝晶狀生長的α相實現(xiàn)了強度與塑性的良好匹配
這些結(jié)果表明,固溶+單級時效處理、固溶+雙級時效處理、固溶+隨爐冷卻處理等不同的熱處理工藝,對亞穩(wěn)β鈦合金析出的次生α相及強度和塑性產(chǎn)生不同的影響
Ti-6Mo-5V-3Al-2Fe-2Zr (%,質(zhì)量分數(shù))合金是一種新型的亞穩(wěn)β鈦合金,基于Mo當(dāng)量準則和d-電子成分設(shè)計方法設(shè)計,其Mo當(dāng)量為12.15,Bo、Md值分別為2.7823、2.3765
作為一種新型亞穩(wěn)β鈦合金,熱處理工藝對其組織、強度和塑性的影響尚不十分清楚
鑒于此,本文對該合金分別進行固溶+單級時效處理、固溶+雙級時效處理以及固溶+隨爐冷卻處理,研究熱處理工藝對Ti-6Mo-5V-3Al-2Fe-2Zr合金的次生α相以及強度和塑性的影響
1 實驗方法
實驗用材料為亞穩(wěn)β鈦合金Ti-6Mo-5V-3Al-2Fe-2Zr (%,質(zhì)量分數(shù))
將高純海綿鈦、Al-Mo中間合金、Al-V中間合金、純鐵和海綿鋯經(jīng)過兩次真空自耗熔煉,得到直徑為12 mm的亞穩(wěn)β鈦合金Ti-6Mo-5V-3Al-2Fe-2Zr (%,質(zhì)量分數(shù))鑄錠,對其在β相區(qū)鍛造得到合金板材
用電火花線切割在板材上切取實驗用試樣
采用公式法和金相法測定該合金的相變點
根據(jù)加入不同合金元素后合金相轉(zhuǎn)變溫度的變化估算合金的相變點 [15]
℃Tβi=882℃+∑fi(xi)
(1)
式中的882℃為純鈦的相轉(zhuǎn)變溫度,fi (xi )為合金中各元素對相變點的影響值
使用 式(1)計算出該合金相變點的理論值為856.24℃
在該值附近選取不同溫度,用金相法測量相變點,最終確定該合金β相轉(zhuǎn)變溫度為855℃±5℃
本文的研究對象為次生α相,因此選擇β相轉(zhuǎn)變點(870℃)以上的溫度進行固溶處理,一生成單一β相組織,從而避免初生α相對實驗結(jié)果的影響
根據(jù)文獻[16,17],以典型的600℃/8 h時效處理作為本實驗的單級時效處理制度,以典型的400℃/2 h預(yù)時效處理作為本實驗雙級時效的預(yù)時效處理制度
為了便于對比,以600℃作為隨爐冷卻的初始溫度
將切取的試樣分別進行固溶+單級時效處理(HT1)、固溶+雙級時效處理(HT2)和固溶+隨爐冷卻處理(HT3),熱處理工藝在圖1中給出
圖1
圖1合金的熱處理工藝
Fig.1Heat treatment process (a) solution and single-stage aging; (b) solution and two-stage aging; (c) solution and furnace cooling
是用Nordlys Nano型EBSD探測器觀察和分析電解拋光后試樣的晶粒尺寸和析出相 (拋光液為6%高氯酸+35%正丁醇+59%甲醇),步長為0.04 μm
使用腐蝕液(氫氟酸∶硝酸∶水=1∶3∶7)腐蝕經(jīng)過金相砂紙打磨、機械拋光后的合金試樣表面,用S-3400N型掃描電子顯微鏡觀察試樣的顯微組織
使用WDW-100型電子萬能試驗機分別對三種熱處理后的試樣進行室溫拉伸實驗,以測定其拉伸性能,計算其抗拉強度、屈服強度以及斷后伸長率
使用S-3400N型掃描電子顯微鏡觀察斷口形貌,分析其斷裂形式
2 實驗結(jié)果2.1 顯微組織
圖2給出了熱處理前Ti-6Mo-5V-3Al-2Fe-2Zr合金的EBSD圖像,可見其組織全部為β相
圖2
圖2熱處理前合金的EBSD圖像
Fig.2EBSD image of the alloy before heat treatment
圖3給出了經(jīng)過不同工藝的熱處理后Ti-6Mo-5V-3Al-2Fe-2Zr合金的顯微組織
由圖3a和3b可見,經(jīng)過HT1處理后在β晶界處生成了連續(xù)的晶界α相(αgb);在β晶粒內(nèi)析出了短棒狀次生α相(αi)
由圖3c和3d可見,經(jīng)過HT2處理后在β晶界處也生成了連續(xù)的αgb相,但是在β晶粒內(nèi)析出的αi相數(shù)量更多且大部分尺寸較小
其原因是,在預(yù)時效階段生成的ω相在后續(xù)高溫時效階段促進αi相的形核從而生成了細小彌散的αi相[18~21]
但是,由圖3d可見,一些優(yōu)先形核的αi相在后續(xù)高溫時效階段充分的生長而使部分αi相長大而粗化
由圖3e和3f可見,經(jīng)過HT3處理后在β晶界處生成了由αgb相形核并向晶內(nèi)平行生長的αwgb相,在β晶粒內(nèi)析出的αi相由短棒狀變?yōu)獒槧?,寬度明顯減小且間距變窄
圖3
圖3不同熱處理后合金的顯微組織
Fig.3Microstructure of the alloy after different heat treatment (a) HT1, grain boundary; (b) HT1, intragranular; (c) HT2, grain boundary; (d) HT2, intragranular; (e) HT3, grain boundary; (f) HT3, intragranular
圖4給出了經(jīng)過不同熱處理的合金的EBSD圖像
圖4a、b、c的解析率分別為96.23%、96.12%和95.56%,三者的解析率較高且差異較小
用EBSD進一步分析了次生α相
結(jié)果表明,經(jīng)過HT1、HT2、HT3處理后合金的β晶粒內(nèi)析出的αi相尺寸逐漸減小,且在β晶界處均生成了連續(xù)的αgb相;與HT1和HT2相比,經(jīng)過HT3處理后合金的晶界處生成了αwgb相,與圖3中合金的顯微組織相同
用EBSD統(tǒng)計次生α相(αs)的體積分數(shù)φ(αs)并結(jié)合圖3統(tǒng)計αi相的平均間距λ,結(jié)果列于表1
可以看出,不同的熱處理使αs相體積分數(shù)變化的趨勢為,HT2>HT3>HT1;αi相平均間距的變化趨勢為,HT1>HT2>HT3
圖4
圖4熱處理后合金的EBSD圖像
Fig.4EBSD images of the alloy after different heat treatment (a) HT1; (b) HT2; (c) HT3
Table 1
表1
表1熱處理工藝對αs相體積分數(shù)和αi相平均間距的影響
Table 1Effect of heat treatment on the volume fraction of αs phase and the average spacing of αi phase
Heat treatment
|
φ(αs)/%
|
λ/nm
|
HT1
|
34.8
|
88.75
|
HT2
|
40.3
|
64.85
|
HT3
|
37.5
|
47.15
|
2.2 合金的拉伸性能
合金經(jīng)過不同工藝的熱處理前后的屈服強度(Rp0.2)、抗拉強度(Rm)、斷后伸長率(A)和強塑積(Psp),列于表2
可以看出,經(jīng)過三種工藝的熱處理后合金的強度都大幅度提高;與HT1處理相比,HT2熱處理使合金的屈服強度和抗拉強度提高,斷后伸長率由5.1%降低為4.8%,合金的塑性沒有明顯的變化;HT3處理后合金的屈服強度和抗拉強度進一步提高,其斷后伸長率也明顯提高;在三種熱處理中,HT3處理后合金的強塑積最高,為10.94 GPa%,其強度與塑性匹配最佳
Table 2
表2
表2熱處理對合金拉伸性能的影響
Table 2Effect of heat treatment on tensile properties of the alloy
Heat treatment
|
Rp0.2/MPa
|
St.dev
|
Rm/MPa
|
St.dev
|
A/%
|
St.dev
|
Psp/GPa%
|
Before HT
|
784
|
9
|
891
|
10
|
9.1
|
0.22
|
8.11
|
HT1
|
1099
|
22
|
1196
|
26
|
5.1
|
0.17
|
6.10
|
HT2
|
1256
|
19
|
1352
|
21
|
4.8
|
0.21
|
5.68
|
HT3
|
1324
|
13
|
1421
|
11
|
7.7
|
0.13
|
10.94
|
2.3 合金的斷口形貌
圖5給出了經(jīng)過三種工藝熱處理后合金的拉伸斷口形貌
由圖5可見,HT1處理和HT2處理后合金的拉伸斷口均呈現(xiàn)出冰糖狀特征和較淺的韌窩,其斷裂方式為脆性斷裂
經(jīng)過HT3處理后合金的拉伸斷口同時呈現(xiàn)出沿晶斷裂特征和穿晶斷裂特征,韌窩的數(shù)量更多且尺寸更大,其斷裂方式開始向韌脆混合型斷裂轉(zhuǎn)變,表明合金具有較好的塑性
合金拉伸斷口的觀察結(jié)果,與表2中合金塑性的變化趨勢相符
圖5
圖5不同熱處理后試樣的拉伸斷口的形貌
Fig.5Fracture morphology of tensile specimens after different heat treatment (a) HT1; (b) HT2; (c) HT3
3 討論
亞穩(wěn)β鈦合金的拉伸性能強化機制,包括合金元素于β基體的固溶強化、β晶界強化、初生α相與β基體的界面強化和次生α相析出強化
因此,合金的屈服強度可表示為[22~24]:
Rp0.2=Rν+Rss+Rgb+Rpb+Rpcpt
(2)
式中Rν為單晶摩擦應(yīng)力影響項,Rss為合金元素于β基體的固溶強化影響項,Rgb為β晶界強化影響項,Rpb為初生α相與β基體的界面強化影響項,Rpcpt為次生α相析出強化影響項
對顯微組織的觀察結(jié)果表明,在本文的實驗中未觀察到初生α相,于是 式(2)改為
νRp0.2=Rν+Rss+Rgb+Rpcpt
(3)
根據(jù) 式(3)計算出次生α相析出強化影響量為
νRpcpt,exp=Rp0.2,exp–(Rν+Rss+Rgb)
(4)
式中Rpcpt, exp為次生α相析出強化影響量,Rp0.2, exp為合金的屈服強度,Rν+Rss+Rgb的值則等于熱處理前合金的屈服強度
由此計算出的Rpcpt, exp數(shù)值,列于表3
Table 3
表3
表3不同熱處理后合金中次生α相的析出強化影響量
Table 3αs precipitation strength after different heat treatment
Heat
treatment
|
Rp0.2,exp
/MPa
|
Rν+Rss+Rgb
/MPa
|
Rpcpt,exp
/MPa
|
HT1
|
1099
|
784
|
315
|
HT2
|
1256
|
784
|
472
|
HT3
|
1324
|
784
|
540
|
由表3可見,經(jīng)過不同工藝的熱處理后生成的次生α相的體積分數(shù)、相間距等明顯不同,進而影響合金強度的變化
文獻[25]證實,次生α相的體積分數(shù)、相間距是熱處理后亞穩(wěn)β鈦合金強度的主要影響因素
圖6給出了經(jīng)過不同工藝的熱處理后合金中次生α相體積分數(shù)φ(αs)、αi相平均間距λ與次生α相析出強化影響量Rpcpt,exp之間的關(guān)系
由圖6a可見,φ(αs)與Rpcpt,exp之間的關(guān)系不是線性的,表明次生α相的體積分數(shù)并不是該合金強度變化的決定因素
由圖6b可見,隨著λ的增大Rpcpt,exp逐漸減小,表明αi相平均間距決定了合金強度的變化
圖6
圖6Rpcpt,exp與φ(αs )和λ的關(guān)系
Fig.6Dependence of Rpcpt,exp on φ(αs ) and λ (a) the dependence of Rpcpt,exp on φ(αs ); (b) the dependence of Rpcpt,exp on λ
位錯的運動很難繞過密排六方結(jié)構(gòu)的αi相[26~28],因此合金中的大量αi/β界面能有效地阻礙位錯的滑移,使其在αi/β界面處大量堆積
因此,可用位錯堆積模型解釋次生α相的強化
位錯堆積前端的局部應(yīng)力為Nτb,αi/β界面阻礙位錯運動而產(chǎn)生的排斥力為τ*b,在平衡狀態(tài)下[29]
Nτb=τ*b
(5)
式中τ為位錯運動施加的應(yīng)力;τ*為αi/β界面產(chǎn)生的應(yīng)力場,其值與位錯源的位置以及界面能量有關(guān),b為伯格斯矢量
同時,堆積位錯的數(shù)量可表示為[30]
πN=π(1-v)τλ/2Gb
(6)
式中v為泊松比;G為剪切模量
設(shè)位錯源位于兩個αi相之間,λ/2為位錯的運動距離,則根據(jù) 式(5)和 式(6)可得位錯滑移穿過αi/β界面的臨界應(yīng)力
πτc=2Gbτ*π(1-v)τλ=k0/λ
(7)
式中k0為材料常數(shù)
式(7)表明,τc與λ-1/2呈線性關(guān)系
圖7給出了不同工藝熱處理后合金的屈服強度與λ-1/2的關(guān)系
可以看出,整體呈現(xiàn)出近似線性相關(guān)的關(guān)系,與 式(7)給出的結(jié)論相符,即隨著αi相平均間距的減小合金的強度提高
圖7
圖7Rp0.2與λ-1/2的關(guān)系
Fig.7Dependence of Rp0.2 on λ-1/2 after heat treatment
經(jīng)過HT1和HT2處理的合金,其塑性均較差
其原因是,與被αi相強化的β基體相比,在β晶界處生成的連續(xù)αgb相弱化了晶界,使裂紋易于在αgb/β界面處萌生并沿其擴展,對合金的塑性產(chǎn)生了嚴重的不良影響[31~33]
這也與合金拉伸斷口的沿晶斷裂特征相符
但是,經(jīng)過HT3處理后,在合金的β晶界處生成了由αgb相形核并向晶內(nèi)擴展的αwgb相,不僅為沿晶裂紋擴展提供了更多的路徑,而且消耗了沿晶裂紋的能量,減緩了其擴展速率,從而改善了合金塑性
這也與對合金拉伸斷口的觀察結(jié)果相符
4 結(jié)論
(1) 在三種工藝熱處理的Ti-6Mo-5V-3Al-2Fe-2Zr合金的晶內(nèi)析出了αi相,在晶界生成了連續(xù)的αgb相;與固溶+單級時效處理與固溶+雙級時效處理相比,固溶+隨爐冷卻處理析出的αi相間距最小,且在晶界處生成了向晶內(nèi)平行生長的αwgb相
(2) 與固溶+單級時效處理及固溶+雙級時效處理相比,固溶+隨爐冷卻處理的Ti-6Mo-5V-3Al-2Fe-2Zr合金強度和塑性匹配最佳,其抗拉強度為1421 MPa,屈服強度為1324 MPa,斷后伸長率為7.7%
(3) 經(jīng)不同工藝的熱處理后Ti-6Mo-5V-3Al-2Fe-2Zr合金晶內(nèi)析出的αi相間距是影響其強度的主要因素,隨著αi相間距的減小合金的強度提高;αwgb相的生成,使合金的塑性顯著改善
參考文獻
View Option 原文順序文獻年度倒序文中引用次數(shù)倒序被引期刊影響因子
[1]
Sun H Y, Zhao J, Liu Y A, et al.
Effect of C addition on microstructure and mechanical properties of Ti-V-Cr burn resistant titanium alloys
[J]. Chin. J. Mater. Res., 2019, 33: 537
DOI [本文引用: 1] " />
用真空自耗熔煉制備了不同C含量的三種阻燃鈦合金鑄錠(直徑120 mm),其名義成分分別為Ti-35V-15Cr、Ti-35V-15Cr-0.075C和Ti-35V-15Cr-0.15C
將鑄錠包套擠壓成直徑為25 mm的棒材,觀察了鑄錠和擠壓棒材的微觀組織,測試并分析了擠壓棒材的室溫拉伸性能、高溫拉伸性能、熱穩(wěn)定性能、高溫蠕變以及持久性能
結(jié)果表明:添加C使阻燃鈦合金熱擠壓后的晶粒顯著細化,使其室溫和高溫拉伸塑性提高;由于碳化物的吸氧作用,添加C的合金熱穩(wěn)定性能顯著提高;添加適量的C可提高阻燃鈦合金的高溫蠕變和持久性能
[2]
Wu X Y, Chen Z Y, Cheng C, et al.
Effects of heat treatment on microstructure, texture and tensile properties of Ti65 alloy
[J]. Chin. J. Mater. Res., 2019, 33: 785
DOI " />
研究了不同熱處理條件下Ti65鈦合金板材的顯微組織和織構(gòu)的變化規(guī)律,分析了板材織構(gòu)的類型和熱處理影響拉伸強度的機制
結(jié)果表明,熱處理對板材的顯微組織和織構(gòu)類型具有顯著的影響
通過熱處理可分別得到具有等軸組織、雙態(tài)組織或片層組織的板材
等軸組織板材的織構(gòu)為晶體c軸與板材RD方向呈現(xiàn)70°~90°夾角的B/T型織構(gòu),雙態(tài)組織和片層組織板材的主要織構(gòu)類型與等軸組織類似,且出現(xiàn)晶體學(xué)c軸與RD方向平行的織構(gòu)
雙態(tài)組織板材內(nèi)的位錯和亞結(jié)構(gòu)使板材的室溫拉伸強度提高,但是對高溫拉伸變形的阻礙能力有限
板材中的織構(gòu)是影響合金力學(xué)性能各向異性的主要因素
經(jīng)980℃/1 h/AC+700℃/4 h/AC熱處理后的板材橫、縱向拉伸強度的差異最小,且都具有較高的室溫拉伸性能和最佳的650℃拉伸性能
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Qin Q H, Peng H B, Fan Q C, et al.
Effect of second phase precipitation on martensitic transformation and hardness in highly Ni-rich NiTi alloys
[J]. J. Alloys Compd., 2018, 739: 873
DOIURL
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Kinetics of dynamic recrystallization of TB6 Ti-alloy during hot compressive deformation at temperatures of β-phase range
[J]. Chin. J. Mater. Res., 2019, 33: 918
歐陽德來, 魯世強, 崔 霞 等.
TB6鈦合金β區(qū)變形的動態(tài)再結(jié)晶動力學(xué)
[J]. 材料研究學(xué)報, 2019, 33: 918
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Liu Y Y, Zhang L, Shi X N, et al.
High cycle fatigue properties and fracture behavior of Ti-5Al-5Mo-5V-1Cr-1Fe titanium alloy
[J]. Rare Met. Mater. Eng., 2018, 47: 3666
DOIURL [本文引用: 1]
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Wang X M, Zhang S Q, Yuan Z Y, et al.
Effect of heat treatment on mechanical properties of Ti-3Al-8V-6Cr-4Mo-4Zr alloy
[J]. Chin. J. Mater. Res., 2017, 31: 409
DOI [本文引用: 1] " />
研究了固溶時效處理對Ti-3Al-8V-6Cr-4Mo-4Zr合金拉伸性能的影響
結(jié)果表明:在800℃/30 min+500℃/12 h處理后,合金的硬度和抗拉強度達到極大值,其延伸率和斷面收縮率沒有明顯的降低
合金的硬度和強度的提高是ω和α析出相共同作用的結(jié)果
在合金的熱軋態(tài)和熱處理態(tài)的斷口都出現(xiàn)了大量的韌窩,表明其為典型的韌性斷裂
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Wang X Y, Yang J R, Zhang K R, et al.
Atomic-scale observations of B2→ω-related phases transition in high-Nb containing TiAl alloy
[J]. Mater. Charact., 2017, 130: 135
DOIURL [本文引用: 1]
[8]
Wang G Q, Zhao Z B, Yu B B, et al.
Effect of heat treatment process on microstructure and mechanical properties of titanium alloy Ti6246
[J]. Chin. J. Mater. Res., 2017, 31: 352
DOI " />
研究了熱處理溫度和冷卻方式對Ti6246合金顯微組織、相組成以及室溫拉伸性能的影響
結(jié)果表明:固溶熱處理后合金的相組成主要與冷卻方式有關(guān)
在β單相區(qū)及(α+β)兩相區(qū)固溶后水冷,β相均轉(zhuǎn)化為α′′馬氏體和少量亞穩(wěn)β相
空冷組織中的β相轉(zhuǎn)變?yōu)楹猩倭看紊料嗟摩罗D(zhuǎn)變組織,隨著熱處理溫度的提高次生α相的含量逐漸增加,尺寸也逐漸增大
時效后組織中的亞穩(wěn)相發(fā)生分解,析出細小的次生α相
固溶后水冷試樣的拉伸曲線上出現(xiàn)“雙屈服”現(xiàn)象,且隨著固溶溫度的提高合金第一屈服點逐漸升高
水淬和空冷合金試樣在595℃/8 h時效后其室溫拉伸強度提高,延伸率及斷面收縮率降低,水淬試樣室溫拉伸性能的變化更大
固溶后空冷且在595℃時效處理的合金,其室溫拉伸性能可達到較好的強塑性匹配
[9]
Wang P Y, Zhang H Y, Zhang Z P, et al.
Effect of solution temperature on microstructure and tensile properties of metastable β-Ti alloy Ti-4Mo-6Cr-3Al-2Sn
[J]. Chin. J. Mater. Res., 2020, 34: 473
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王鵬宇, 張浩宇, 張志鵬 等.
固溶溫度對亞穩(wěn)β鈦合金Ti-4Mo-6Cr-3Al-2Sn的組織和拉伸性能的影響
[J]. 材料研究學(xué)報, 2020, 34: 473
[本文引用: 1]
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Fan J K, Li J S, Kou H C, et al.
Microstructure and mechanical property correlation and property optimization of a near β titanium alloy Ti-7333
[J]. J. Alloys Compd., 2016, 682: 517
DOIURL [本文引用: 1]
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Li C L, Mi X J, Ye W J, et al.
Microstructural evolution and age hardening behavior of a new metastable beta Ti-2Al-9.2Mo-2Fe alloy
[J]. Mat. Sci. Eng., 2015, 645A: 225
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Zheng Y F, Williams R E A, Sosa J M, et al.
The indirect influence of the ω phase on the degree of refinement of distributions of the α phase in metastable β-Titanium alloys
[J]. Acta Mater., 2016, 103: 165
DOIURL [本文引用: 1]
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Ma Q, Cao D.
Effect of double aging treatment on microstructure and mechanical property of TB8 titanium alloy
[J]. Trans. Mater. Heat Treat., 2017, 38(10): 41
[本文引用: 1]
馬 權(quán), 曹 迪.
雙級時效處理對TB8合金組織和性能的影響
[J]. 材料熱處理學(xué)報, 2017, 38(10): 41
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Zhou W, Ge P, Zhao Y Q, et al.
Evolution of primary α phase morphology and mechanical properties of a novel high-strength titanium alloy during heat treatment
[J]. Rare Met. Mater. Eng., 2017, 46: 2852
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Accurate calculation of α+β/β phase transition of titanium alloys based on binary phase diagrams
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基于二元相圖精確計算鈦合金α+β/β相變點
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雙級時效對Ti-25Nb-10Ta-1Zr-0. 2Fe醫(yī)用β鈦合金顯微組織與力學(xué)性能的影響
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Microstructure evolution of ω and α phase of β-CEZ alloy during the solution treatment and aging process
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β-CEZ鈦合金在固溶時效時ω相與α相的組織演化規(guī)律
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DOI [本文引用: 1] class="outline_tb" " />
The ingots with 120 mm diameter of burn resistant Ti-alloys with nominal composition of Ti-35V-15Cr, Ti-35V-15Cr-0.075C and Ti-35V-15Cr-0.15C were produced by vacuum arc consumable smelting. These ingots were deformed into bars with 25 mm diameter by sheathed extrusion. The microstructures of the ingots and extruded bars of burn resistant Ti-alloys were investigated. The tensile property, thermal stability and creep properties of the extruded bars of burn resistant Ti-alloys were tested under different conditions. The results show that burn resistant Ti-alloys with C addition have better ductility in tensile test due to refined grain size resulted from the sheathed extrusion process. Carbide can act as a stable sink for dissolved oxygen in the matrix, to improve the tensile ductility of the alloy even after hot exposure. In sum, the moderate C addition can improve the creep properties of burn resistant Ti-alloys.
孫歡迎, 趙 軍, 劉翊安 等.
C含量對Ti-V-Cr系阻燃鈦合金微觀組織和力學(xué)性能的影響
[J]. 材料研究學(xué)報, 2019, 33: 537
用真空自耗熔煉制備了不同C含量的三種阻燃鈦合金鑄錠(直徑120 mm),其名義成分分別為Ti-35V-15Cr、Ti-35V-15Cr-0.075C和Ti-35V-15Cr-0.15C
將鑄錠包套擠壓成直徑為25 mm的棒材,觀察了鑄錠和擠壓棒材的微觀組織,測試并分析了擠壓棒材的室溫拉伸性能、高溫拉伸性能、熱穩(wěn)定性能、高溫蠕變以及持久性能
結(jié)果表明:添加C使阻燃鈦合金熱擠壓后的晶粒顯著細化,使其室溫和高溫拉伸塑性提高;由于碳化物的吸氧作用,添加C的合金熱穩(wěn)定性能顯著提高;添加適量的C可提高阻燃鈦合金的高溫蠕變和持久性能
[2]
Wu X Y, Chen Z Y, Cheng C, et al.
Effects of heat treatment on microstructure, texture and tensile properties of Ti65 alloy
[J]. Chin. J. Mater. Res., 2019, 33: 785
" />
研究了不同熱處理條件下Ti65鈦合金板材的顯微組織和織構(gòu)的變化規(guī)律,分析了板材織構(gòu)的類型和熱處理影響拉伸強度的機制
結(jié)果表明,熱處理對板材的顯微組織和織構(gòu)類型具有顯著的影響
通過熱處理可分別得到具有等軸組織、雙態(tài)組織或片層組織的板材
等軸組織板材的織構(gòu)為晶體c軸與板材RD方向呈現(xiàn)70°~90°夾角的B/T型織構(gòu),雙態(tài)組織和片層組織板材的主要織構(gòu)類型與等軸組織類似,且出現(xiàn)晶體學(xué)c軸與RD方向平行的織構(gòu)
雙態(tài)組織板材內(nèi)的位錯和亞結(jié)構(gòu)使板材的室溫拉伸強度提高,但是對高溫拉伸變形的阻礙能力有限
板材中的織構(gòu)是影響合金力學(xué)性能各向異性的主要因素
經(jīng)980℃/1 h/AC+700℃/4 h/AC熱處理后的板材橫、縱向拉伸強度的差異最小,且都具有較高的室溫拉伸性能和最佳的650℃拉伸性能
[3]
Qin Q H, Peng H B, Fan Q C, et al.
Effect of second phase precipitation on martensitic transformation and hardness in highly Ni-rich NiTi alloys
[J]. J. Alloys Compd., 2018, 739: 873
[4]
Ouyang D L, Lu S Q, Cui X, et al.
Kinetics of dynamic recrystallization of TB6 Ti-alloy during hot compressive deformation at temperatures of β-phase range
[J]. Chin. J. Mater. Res., 2019, 33: 918
歐陽德來, 魯世強, 崔 霞 等.
TB6鈦合金β區(qū)變形的動態(tài)再結(jié)晶動力學(xué)
[J]. 材料研究學(xué)報, 2019, 33: 918
[5]
Liu Y Y, Zhang L, Shi X N, et al.
High cycle fatigue properties and fracture behavior of Ti-5Al-5Mo-5V-1Cr-1Fe titanium alloy
[J]. Rare Met. Mater. Eng., 2018, 47: 3666
[6]
Wang X M, Zhang S Q, Yuan Z Y, et al.
Effect of heat treatment on mechanical properties of Ti-3Al-8V-6Cr-4Mo-4Zr alloy
[J]. Chin. J. Mater. Res., 2017, 31: 409
" />
研究了固溶時效處理對Ti-3Al-8V-6Cr-4Mo-4Zr合金拉伸性能的影響
結(jié)果表明:在800℃/30 min+500℃/12 h處理后,合金的硬度和抗拉強度達到極大值,其延伸率和斷面收縮率沒有明顯的降低
合金的硬度和強度的提高是ω和α析出相共同作用的結(jié)果
在合金的熱軋態(tài)和熱處理態(tài)的斷口都出現(xiàn)了大量的韌窩,表明其為典型的韌性斷裂
[7]
Wang X Y, Yang J R, Zhang K R, et al.
Atomic-scale observations of B2→ω-related phases transition in high-Nb containing TiAl alloy
[J]. Mater. Charact., 2017, 130: 135
[8]
Wang G Q, Zhao Z B, Yu B B, et al.
Effect of heat treatment process on microstructure and mechanical properties of titanium alloy Ti6246
[J]. Chin. J. Mater. Res., 2017, 31: 352
" />
研究了熱處理溫度和冷卻方式對Ti6246合金顯微組織、相組成以及室溫拉伸性能的影響
結(jié)果表明:固溶熱處理后合金的相組成主要與冷卻方式有關(guān)
在β單相區(qū)及(α+β)兩相區(qū)固溶后水冷,β相均轉(zhuǎn)化為α′′馬氏體和少量亞穩(wěn)β相
空冷組織中的β相轉(zhuǎn)變?yōu)楹猩倭看紊料嗟摩罗D(zhuǎn)變組織,隨著熱處理溫度的提高次生α相的含量逐漸增加,尺寸也逐漸增大
時效后組織中的亞穩(wěn)相發(fā)生分解,析出細小的次生α相
固溶后水冷試樣的拉伸曲線上出現(xiàn)“雙屈服”現(xiàn)象,且隨著固溶溫度的提高合金第一屈服點逐漸升高
水淬和空冷合金試樣在595℃/8 h時效后其室溫拉伸強度提高,延伸率及斷面收縮率降低,水淬試樣室溫拉伸性能的變化更大
固溶后空冷且在595℃時效處理的合金,其室溫拉伸性能可達到較好的強塑性匹配
[9]
Wang P Y, Zhang H Y, Zhang Z P, et al.
Effect of solution temperature on microstructure and tensile properties of metastable β-Ti alloy Ti-4Mo-6Cr-3Al-2Sn
[J]. Chin. J. Mater. Res., 2020, 34: 473
王鵬宇, 張浩宇, 張志鵬 等.
固溶溫度對亞穩(wěn)β鈦合金Ti-4Mo-6Cr-3Al-2Sn的組織和拉伸性能的影響
[J]. 材料研究學(xué)報, 2020, 34: 473
[10]
Fan J K, Li J S, Kou H C, et al.
Microstructure and mechanical property correlation and property optimization of a near β titanium alloy Ti-7333
[J]. J. Alloys Compd., 2016, 682: 517
[11]
Li C L, Mi X J, Ye W J, et al.
Microstructural evolution and age hardening behavior of a new metastable beta Ti-2Al-9.2Mo-2Fe alloy
[J]. Mat. Sci. Eng., 2015, 645A: 225
[12]
Zheng Y F, Williams R E A, Sosa J M, et al.
The indirect influence of the ω phase on the degree of refinement of distributions of the α phase in metastable β-Titanium alloys
[J]. Acta Mater., 2016, 103: 165
[13]
Ma Q, Cao D.
Effect of double aging treatment on microstructure and mechanical property of TB8 titanium alloy
[J]. Trans. Mater. Heat Treat., 2017, 38(10): 41
馬 權(quán), 曹 迪.
雙級時效處理對TB8合金組織和性能的影響
[J]. 材料熱處理學(xué)報, 2017, 38(10): 41
[14]
Zhou W, Ge P, Zhao Y Q, et al.
Evolution of primary α phase morphology and mechanical properties of a novel high-strength titanium alloy during heat treatment
[J]. Rare Met. Mater. Eng., 2017, 46: 2852
[15]
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C含量對Ti-V-Cr系阻燃鈦合金微觀組織和力學(xué)性能的影響
1
2019
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