原位自生相增强Ti-Zr-Cu-Pd-Mo非晶复合材料的制备及其力学性能

非晶合金的原子排布是短程有序和长程无序，具有高硬度、高强度和大弹性极限等力学性能[1] 块状非晶合金是一种具有极大应用前景的候选生物医用材料[2] 传统晶态金属材料的杨氏模量是人体骨骼组织的10~20倍，植入人体后与骨骼模量不匹配，使骨骼负荷不足，产生“应力屏蔽”而引起骨质疏松，不利于骨愈合 非晶合金的杨氏模量较低、弹性极限较高，能随着骨骼的自然弯曲而弹性弯曲，使应力分布更加均匀，减弱了应力屏蔽效应，可提高骨组织的愈合速率[3]

钛基非晶合金兼具钛合金和非晶合金的特点，其密度低、生物相容性良好[4]、耐蚀性高[5]和与骨组织杨氏模量匹配[6]，有广阔的应用前景[7] Zhu等[8]用Pd元素替代Ti-Ni-Cu和Ti-Zr-Cu-Ni非晶合金体系中具有细胞毒性的Ni元素，研发出一种新型Ti-Zr-Cu-Pd 4元非晶合金体系 与传统的Ti基非晶合金相比，该体系不含Ni、Al和Be等有毒元素，更适用于生物医用领域 这个体系中的Ti40Zr10Cu36Pd14(原子比，下同)其临界尺寸达到7 mm，晶化焓为287.6 kJ/mol，具有很高的玻璃形成能力和热稳定性

在非晶合金的室温变形过程中发生一种特有的剪切局域化和应变软化，使其室温塑性极低[9] 研究表明，在非晶基体中引入塑性晶化增强相可提高其室温塑性 [10] Ti合金中的Mo元素是一种重要的β-Ti相稳定化元素，能细化钛合金晶粒，使β钛合金的稳定性和强度提高[11] Mo不仅易与Zr或Ti生成无限固溶体，还能显著降低β/(α + β)相变温度并扩展β相稳定区域[12~14] 本文在非晶形成能力较高、且不含有毒性元素的Ti40Zr10Cu36Pd14非晶合金中微添加Mo元素，使其在凝固过程中原位析出内生塑性β-Ti相，研究不同Mo添加量合金的组织和力学性能

1 实验方法

实验用块体合金原料Ti、Zr、Cu、Pd和Mo的纯度高于99.99% (质量分数) 按照(Ti0.4Zr0.1Cu0.36Pd0.14)100 - x Mo x (x =0，1，2，5，原子分数，分别记为Mo0，Mo1，Mo2，Mo5)配料，在熔融Ti锭吸氧和高纯氩气(> 99.999%，质量分数)保护下用电弧炉熔炼母合金 为了确保母合金锭的成分均匀，合金锭反复熔炼至少5次 将炼好的合金锭破碎并清洗后装入石英管，用铜模喷铸法制备出直径为2 mm的棒状试样

用XRD-7000型X射线衍射仪(XRD，CuKα )分析棒状试样的相组成，用GeminiSEM300场发射扫描电子显微镜观察试样的微观组织和断口形貌 用Zwick Z020型万能材料试验机进行压缩实验，试样的长径比为2∶1，将其两端面磨平并使其垂直于受力方向，应变速率为5.0 × 10-4 s-1

2 结果和讨论2.1 微观组织

图1给出了4种不同Mo含量的Ti基非晶复合材料试样的XRD谱 可以看出，在Mo0试样(没添加Mo元素)和Mo1试样(添加1%Mo)的谱中只有一个明显的弥散非晶衍射峰，没有出现晶体峰 而在Mo2与Mo5样品的谱中除了非晶衍射峰，还出现了尖锐的晶化峰(标定为β-Ti相) 这表明，在Mo2和Mo5中析出了β-Ti相 从XRD谱中还可见，随着Mo含量的提高β-Ti相的衍射峰强度逐渐提高，表明样品中β-Ti的含量随之提高

图1



图1Ti基非晶复合材料的XRD谱

Fig.1XRD patterns of Ti-based amorphous composites

图2给出了Mo0、Mo1和Mo2试样的SEM图像 从图2a和图2b可见，Mo0和Mo1试样由没有明显对比的均匀非晶相组成，没有生成晶化相，与图1中XRD谱给出的结果一致；而在图2c(Mo2)中除了非晶基体还有点状的析出相，但是因析出相的成分与基体相近而对比度不高 因此，对Mo2进行了Mo元素的面扫 在图2d中可清晰观察到析出相的形貌，图像分析结果给出β-Ti相的体积分数约为10%，平均尺寸约为8 μm

图2



图2不同Mo含量样品的SEM照片和Mo元素的分布

Fig.2SEM images of samples at different Mo contents (a) Mo0; (b) Mo1; (c) Mo2 and (d) distribution of Mo element in (c) -plot

上述结果表明，由于Mo在Ti中的固溶度较高，当添加量≤ 1%时Mo元素全部固溶进入基体，难以促进β-Ti相的析出 当Mo添加量≥ 2%时在非晶基体中析出β-Ti相，生成原位自生钛基非晶复合材料且β-Ti相弥散均匀分布

为了提高样品中β-Ti相的体积分数，制备了Mo5试样(Mo元素的含量为5%)，其SEM照片和对应的元素面扫图像如图3所示 由图3a可以看出，随着Mo含量的提高Mo5中的β-Ti相的体积分数随之提高且尺寸更大 分析结果给出了Mo5中β-Ti相的体积分数为20%，平均尺寸为15 μm 图3b~f中的元素面扫分布结果表明，复合材料中的非晶基体由均匀分布的Ti、Zr、Cu和Pd 4种元素组成，析出的β-Ti相则主要由Ti和Mo元素组成

图3



图3Mo5试样的SEM照片对应的元素面扫图

Fig.3SEM images of Mo5 specimens (a) and corresponding elemental face sweeps of Ti (b), Zr (c), Cu (d), Pd (e) and Mo (f)

2.2 力学性能

图4给出了不同Mo添加量样品的压缩真应力-真应变曲线，可见所有试样均表现出一定的塑性变形量，而Mo2和Mo5出现了明显的加工硬化现象 随着Mo含量的提高试样的断裂强度和塑性均随之提高 不含Mo的基体合金其断裂强度为1992 MPa，压缩塑性为1.2%；Mo1的断裂强度为2057 MPa，比基体提高了3.3%，塑性为1.7%，比基体有所提高；Mo2和Mo5的断裂强度分别为2422和2630 MPa，塑性分别为3.9%和7.3%，强度比基体分别提高了21.6%和32.0%，塑性比基体分别提高了2.25倍和5.08倍(表1) 上述结果表明，Ti基非晶基体中β-Ti相的析出显著提高了非晶复合材料的室温压缩性能，且β-Ti相的体积分数越高其增强效果越显著

图4



图4不同Mo含量试样的室温压缩真应力-应变曲线

Fig.4Room temperature compression true stress-strain curves for specimens with different Mo contents

Table 1

表1

表1不同Mo含量的Ti基非晶复合材料的杨氏模量E、断裂强度σf、屈服强度σy、断裂应变εf、屈服应变εp和加工硬化指数n

Table 1Young′s modulus E, fracture strength σf, yield strength σy, fracture strain εf, yield strain εp and work hardening index n of Ti-based amorphous composites with different Mo contents

Sample	E / GPa	σf / MPa	σy / MPa	εf / %	εp / %	n
Mo0	122	1992	1850	2.7	1.2	-
Mo1	128	2057	1912	3.2	1.7	-
Mo2	113	2422	1818	5.5	3.9	0.14
Mo5	105	2630	1772	9.0	7.3	0.20

非晶复合材料在室温加载时其中的韧性第二相先屈服变形，随着应力的增大基体中的剪切带形核并扩展[15] 基体中的剪切带在扩展过程中可能绕过韧性相产生分枝或在与第二相的界面停止扩展，也可能在界面增殖生成二次剪切带，最终形成多重剪切带[16] 每条剪切带对应部分塑性变形量，多重剪切带的生成使复合材料的塑性提高，避免了基体内部高度局域化的剪切带失稳转变为剪切带而发生脆性断裂[17] 为了进一步探究不同Mo添加量非晶复合材料的变形机理，对比了Mo0和Mo5试样的压缩断口SEM照片(图5) 图5a、b给出了Mo0试样的断口SEM图像 可以看出，在试样侧面产生了与断面平行的剪切带，但是数量较少，且断面呈非晶合金典型的河流状花样[18] 图5c、d给出了Mo5试样的断口SEM图像，可见比Mo0断裂后侧面产生的剪切带更为明显、数量更多，还产生了大量垂直于断裂方向的二次剪切带 这表明，在变形过程中剪切带的扩展受到原位β-Ti相的阻碍而发生偏转或增殖 Mo5断面不仅呈现出非晶合金经典的河流状花样，还存在大片局部熔化区与β-Ti相，表明剪切带与第二相发生了强烈的交互作用 在非晶复合材料中存在一种特征值，称为加工区域尺寸(Processing zone)[19] 复合组织中第二相的尺寸和相间距越接近此加工区域的尺寸，复合材料的力学性能越优异，这与基体内裂纹前端的张开位移有关 研究表明，Ti基非晶的加工区域尺寸约为20 μm[19] 上述组织分析已给出Mo5中第二相的平均尺寸约为15 μm，体积含量约为20%，由λ = dππ/6f3 (d为平均尺寸，f为体积含量，λ为平均间距)[20]，可计算出Mo5中β-Ti相的平均相间距约为21 μm 可以看出，Mo5中第二相的尺寸与相间距与基体的加工区域尺寸十分接近，表明Mo5中第二相与基体间的交互作用增强，更能提高剪切带的稳定性，抑制剪切带向裂纹的失稳转变，提高材料的综合力学性能

图5



图5不同Mo含量Ti基非晶复合材料的压缩断口及其侧面SEM图像

Fig.5Compression fractures of the samples with different Mo contents and their lateral SEM images (a, b) Mo0; (c, d) Mo5

析出β-Ti相除了使室温塑性显著提高，还使Mo2、Mo5发生明显的加工硬化，表1列出了其加工硬化指数 由表1可见，随着β-Ti相析出量的增多复合材料的加工硬化指数逐渐增大 纯非晶合金中局域剪切带的温升使其在变形过程中发生加工软化(如图4中的曲线Mo1所示)，不利于其实际应用，与其相比，非晶复合材料中析出晶化相的变形使其发生硬化现象

3 结论

(1) Mo元素添加量(原子分数)较低(≤ 1%)的Ti40Zr10Cu36Pd14非晶合金，仍为纯非晶合金；在Mo元素添加量≥ 2%的合金中析出均匀分散的细小原位β-Ti相，成为原位塑性β-Ti相增强的Ti基非晶复合材料

(2) 随着Mo含量的提高β-Ti相的体积分数提高和平均尺寸增大，得到的复合材料的模量逐渐降低，强度和塑性提高

(3) 在复合材料的变形过程中塑性β-Ti相能阻碍剪切带的快速扩展，使剪切带发生增殖和偏转，生成多重剪切带，提高了材料的室温塑性；同时，β-Ti相的平均尺寸和相间距与基体的加工区域尺寸匹配，增强了第二相与基体间的交互作用，提高了剪切带的稳定性 在复合材料的变形过程中作为塑性相的β-Ti发生形变使其发生明显的加工硬化

参考文献

View Option 原文顺序文献年度倒序文中引用次数倒序被引期刊影响因子

[1]

Zhai W, Chang J, Geng D L, et al.

Progress and prospect of solidification research for metallic materials

[J]. Chin. J. Nonferrous Met., 2019, 29(9): 1953

[本文引用: 1]

翟 薇, 常 健, 耿德路 等.

金属材料凝固过程研究现状与未来展望

[J]. 中国有色金属学报, 2019, 29(9): 1953

[本文引用: 1]

[2]

Qiu K Q, Yang J B, You J H, et al.

Glass-forming ability and mechanical properties for Mg-Zn-Ca alloys

[J]. Chin. J. Nonferrous Met., 2011, 21(8): 1828

[本文引用: 1]

邱克强, 杨君宝, 尤俊华 等.

Mg-Zn-Ca合金的非晶形成能力及力学性能

[J]. 中国有色金属学报, 2011, 21(8): 1828

[本文引用: 1]

[3]

Li B Y, Rong L J, Li Y Y.

Stress-strain behavior of porous Ni-Ti shape memory intermetallics synthesized from powder sintering

[J]. Intermetallics, 2000, 8(5-6): 643

DOIURL [本文引用: 1]

[4]

Xie G Q, Kanetaka H, Kato H, et al.

Porous Ti-based bulk metallic glass with excellent mechanical properties and good biocompatibility

[J]. Intermetallics, 2019, 105: 153

DOIURL [本文引用: 1]

[5]

He G, Eckert J, L?ser W.

Stability, phase transformation and deformation behavior of Ti-base metallic glass and composites

[J]. Acta Mater., 2003, 51(6): 1621

DOIURL [本文引用: 1]

[6]

Sugiyama N, Xu H Y, Onoki T, et al.

Bioactive titanate nanomesh layer on the Ti-based bulk metallic glass by hydrothermal-electrochemical technique

[J]. Acta Biomater., 2009, 5(4): 1367

DOIPMID [本文引用: 1] " />

The microstructure and tension ductility of a series of Ti-based bulk metallic glass matrix composite (BMGMC) is investigated by changing content of the β stabilizing element vanadium while holding the volume fraction of dendritic phase constant. The ability to change only one variable in these novel composites has previously been difficult, leading to uninvestigated areas regarding how composition affects properties. It is shown that the tension ductility can range from near zero percent to over ten percent simply by changing the amount of vanadium in the dendritic phase. This approach may prove useful for the future development of these alloys, which have largely been developed experimentally using trial and error.

[13]

Zhai H M, Wang H F, Liu F.

Effects of Sn addition on mechanical properties of Ti-based bulk metallic glass composites

[J]. Mater. Des., 2016, 110: 782

DOIURL

[14]

Zhang L, Zhang H F, Li W Q, et al.

β-type Ti-based bulk metallic glass composites with tailored structural metastability

[J]. J. Alloys Compd., 2017, 708: 972

DOIURL [本文引用: 1]

[15]

Zhao J X.

Understanding the shear band interaction in metallic glass

[J]. Philos. Mag. Lett., 2016, 96(1): 35

DOIURL [本文引用: 1]

[16]

Qiao J W, Zhang Y, Liaw P K, et al.

Micromechanisms of plastic deformation of a dendrite/Zr-based bulk-metallic-glass composite

[J]. Scr. Mater., 2009, 61(11): 1087

DOIURL [本文引用: 1]

[17]

Inoue A.

Stabilization of metallic supercooled liquid and bulk amorphous alloys

[J]. Acta Mater., 2000, 48(1): 279

DOIURL [本文引用: 1]

[18]

Sun B A, Wang W H.

The fracture of bulk metallic glasses

[J]. Prog. Mater. Sci., 2015, 74: 211

DOIURL [本文引用: 1]

[19]

Xi X K, Zhao D Q, Pan M X, et al.

Fracture of brittle metallic glasses: Brittleness or plasticity

[J]. Phys. Rev. Lett., 2005, 94(12): 125510

DOIURL [本文引用: 2]

[20]

Wang Z, Georgarakis K, Nakayama K S, et al.

Microstructure and mechanical behavior of metallic glass fiber-reinforced Al alloy matrix composites

[J]. Sci. Rep., 2016, 6(1): 24384

DOI [本文引用: 1] class="outline_tb" " />

Titanate nanomesh layers were fabricated on Ti-based bulk metallic glass (BMG) to induce bioactivity in the form of apatite-forming ability. Titanate nanomesh layers were prepared by hydrothermal-electrochemical treatment at 90 degrees C for 2 h, with an aqueous solution of NaOH as an electrolyte. A constant electric current of 0.5 mA cm(-2) was applied between the BMG substrate and a Pt electrode acting as the anode and cathode, respectively. A nanomesh layer, consisting of nanowires (approximately 20 nm in diameter) formed on the BMG. An immersion test in simulated body fluid for 12 days revealed that the titanate nanomesh layer on the BMG promoted the growth of bone-like hydroxyapatite.

[7]

Li J, Li Z C, Chen D J.

Biocompatibility of new titanium alloy TZNT for surgical implant application

[J]. Chin. J. Nonferrous Met., 2010, 20(4): 756

李 军, 李佐臣, 陈杜娟.

新型外科植入用钛合金TZNT的生物相容性

[J]. 中国有色金属学报, 2010, 20(4): 756

[8]

Zhu S L, Wang X M, Qin F X, et al.

New TiZrCuPd quaternary bulk glassy alloys with potential of biomedical applications

[J]. Mater. Trans., 2007, 48(9): 2445

[9]

Xu F, Long Z L, Peng J, et al.

Atomic force microscope nanoindentation behavior of shear bands of bulk metallic glasses

[J]. Chin. J. Nonferrous Met., 2011, 21(6): 1444

许 福, 龙志林, 彭 建 等.

块体非晶合金剪切带的原子力纳米压痕行为

[J]. 中国有色金属学报, 2011, 21(6): 1444

[10]

Gu X J, Poon S J, Shiflet G J, et al.

Compressive plasticity and toughness of a Ti-based bulk metallic glass

[J]. Acta Mater., 2010, 58(5): 1708

[11]

Wada T, Setyawan A D, Yubuta K, et al.

Nano- to submicro-porous β-Ti alloy prepared from dealloying in a metallic melt

[J]. Scr. Mater., 2011, 65(6): 532

[12]

Kolodziejska J A, Kozachkov H, Kranjc K, et al.

Towards an understanding of tensile deformation in Ti-based bulk metallic glass matrix composites with BCC dendrites

[J]. Sci. Rep., 2016, 6(1): 22563

" />

Metallic glass-reinforced metal matrix composites are an emerging class of composite materials. The metallic nature and the high mechanical strength of the reinforcing phase offers unique possibilities for improving the engineering performance of composites. Understanding the structure at the amorphous/crystalline interfaces and the deformation behavior of these composites is of vital importance for their further development and potential application. In the present work, Zr-based metallic glass fibers have been introduced in Al7075 alloy (Al-Zn-Mg-Cu) matrices using spark plasma sintering (SPS) producing composites with low porosity. The addition of metallic glass reinforcements in the Al-based matrix significantly improves the mechanical behavior of the composites in compression. High-resolution TEM observations at the interface reveal the formation of a thin interdiffusion layer able to provide good bonding between the reinforcing phase and the Al-based matrix. The deformation behavior of the composites was studied, indicating that local plastic deformation occurred in the matrix near the glassy reinforcements followed by the initiation and propagation of cracks mainly through the matrix. The reinforcing phase is seen to inhibit the plastic deformation and retard the crack propagation. The findings offer new insights into the mechanical behavior of metal matrix composites reinforced with metallic glasses.

Progress and prospect of solidification research for metallic materials

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