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elements in Mg[11, 31, 47] 图4 共晶相对镁合金氧化行为影响[11] Fig. 4 Effect of eutectic phase on oxidation behavior of magnesium alloy[11] 2.3 金属间化合物(第二相) 金属间化合物是影响合金阻燃性的重要因素.由表1可知,Al和Zn对应氧化物的PBR均在1~2之间,但事实上Mg与Al,Zn等常用元素合金化并不能提高合金的燃点,原因是Mg易与其形成低熔点第二相[48-49].镁合金的高温氧化通常伴随着组织的变化和第二相的熔化[19],低熔点相会降低合金的燃点.镁合金的低熔点相在高温时会率先熔化,第二相在合金中形成液态区域,加速了Mg的蒸发和氧化物结节的生长.此外,来自低熔点相的较高的蒸气压会促进多孔氧化层的形成和裂纹的生长,使表面生成的保护性氧化层破裂......
the ordering temperature by 75 K and 50 K, respectively; while additive Pd, Cr and Cu increase the ordering temperature by 150 K, 200 K and 200 K. For (FePt)85B15 film in thickness of 10 nm..., Cr, Cu, B) chemically-synthesized nano-particles and (FePt)85B15 film with 10 nm in thickness[29-31] Decrease of the activation energy, i.e. ordering temperature, for Ag and Au-doped Fe-Pt nano......
conventional machining of Al2O3, ZrO2-Al2O3 and Si3N4 ceramics. LIU et al[6] showed a relationship between surface roughness and material strength. Results showed the enhancement of strength with lower... due to the high cutting temperature and the extreme hardness of work materials. WANG et al[11] introduced liquid nitrogen (LN) cooling to control the temperature in the cutting zone. Results showed......
NiAl合金的塑性和韧性,从1993年开始,本文作者等研究了纳米晶NiAl合金及其复合材料的制备工艺,组织结构与力学性能. 3.1 纳米晶NiAl的制备,力学性能与热稳定性 利用机械合金化(MA)方法,在高能球磨机中球磨按比例配制的Ni粉和Al粉混合粉末,通过爆炸反应生成纳米晶NiAl粉末,平均晶粒粒径可达几纳米[20].然后,选择合适的热压条件将NiAl纳米晶粉末制成纳米块体材料.在...上的晶粒细化对其室温到高温强度及塑性均无明显影响,这与普通的金属及高温合金明显不同.而对于非化学计量比的NiAl,晶粒粒径细化却使其低温强度得到大幅度提高.2种复合材料的基体成分有些偏离化学计量比,对NiAl-20%TiB2(体积分数)而言为Ni-(49.2±0.5)%Al(摩尔分数),而对NiAl-20%TiC(体积分数)而言为Ni-(48.7±0.5)%Al(摩尔分数),所以,在界面结 合良......
coating film[J]. The Chinese Journal of Nonferrous Metals, 2006, 16(5): 847-852. [13] 解 挺, 焦明华, 俞建卫, 吴玉程, 张立德. 准一维纳米材料制备方法的研究现状和发展趋势[J]. 材料科学与工程学报, 2006, 24(2): 311-315. XIE Ting, JIAO Ming-hua, YU Jian..., SUN Jia-yue. Preparation and characterization of room-temperature ferromagnetic Ni-doped TiO2 nanobelts[J]. Acta Phys-Chim Sin, 2008, 24(4): 607-611. [86] 李洪义, 王金淑, 冉 津, 周美玲. 热处理温度对TiO2纳米管阵列薄膜光生阴极保......
空气氛下,金刚石磨粒发生热损伤的温度高达2 100 ℃;因此,为避免高温下金刚石磨粒发生热损伤,高频感应钎焊和激光钎焊等高温钎焊应在惰性气体或真空保护中进行.李嘉[8]采用激光钎焊方法,通过优化激光功率,光斑大小和离焦率等工艺参数将钎焊温度控制在1 050 ℃,并在氩气气体保护下连接Ag-Cu-Ti或Ni-Cr-B-Si活性钎料与金刚石磨粒,使金刚石磨粒与钎料合金的界面形成化学冶金结合.选择合适的...美好的应用前景[10].常用于钎焊金刚石线锯钎料的合金体系有Ni-B-Cr-基体合金,Cu-Sn-Ti和Cu-Ag-Ti等[11].张发垒等[7]以Ni-Cr-B-Si为焊料,在氩气氛围下通过高频感应线圈加热钎焊,成功研制出直径为0.8 mm,把持力较强的固结磨粒金刚石线锯.HIGASHI等[12]为避免在钎焊温度超过600 ℃下线锯基体SUS-304的降解,向47.5%Ag-25.5......
]. During laser welding, it is very difficult to avoid these decompositions. However, DAHOTRE et al [32] showed that decreasing the specific energy during laser melting could reduce the formation... [35]. In order to quantitatively assess the tool wear, LIU et al [9] used the percent variation (rw), given by Eq. (1), in tool size as evaluation index.  ......
Inconel718模具钢的挤压使用寿命相比H13钢的更好,达到40次以上,而H13钢热挤压30次左右模具工作带位置出现严重磨损.Inconel718模具钢磨损机制与H13钢相似,主要为粘着磨损和磨粒磨损.强烈的铝粘模化学现象导致Ni-Al-Si-Mo-Ti-Cr-Fe-Zn-O金属间混合物的形成.在工作带位置高拉应力的作用下该混合物会发生剥落.同时剥落的混合物和界面形成的铝合金氧化层共同起磨粒作用使模具钢...结合,组织细密,无孔隙.陈慧敏等[27]采用真空粉末烧结法在H13模具钢表面获得了深度为1~3 mm的三元硼化物(Mo2FeB2)基金属陶瓷覆层,覆层和钢基体通过 Fe,B,Cr,Ni等相互扩散渗透牢固结合,硬度达到1200 HV,使钢表面耐磨性能大幅度提高. 表面化学热处理工艺中,普通渗氮应用最为广泛,成本低,可靠性高;与普通渗氮相比,多元共渗和复合处理的效果最好,渗层比较深;离子注入可提高表面......
of the environment [34]. Some studies on AMMCs reinforced with BLA particles were reported [35-37]. ALANEME et al [35] studied the aluminium hybrid composite (Al-Mg-Si/ BLA/Al2O3) with variations of BLA... as a complementing reinforcement would produce the high performance and low cost composites. ALANEME et al [36] compared the mechanical and corrosion resistance of Al-Mg-Si/SiC AMMCs and Al-Mg-Si/SiC......
with copper oxide nanoparticles among others. The review published by LIU et al [7] presented experimental results obtained for the heat pipe and nanofluid combination applied to several kinds... by this heat pipe. Newer reviews were published by BUSCHMANN [8] and SURESHKUMAR et al [9], and also obtained similar results regarding the heat transfer performance. The existing analytical studies......