文玉华
,
张伟
,
李宁
,
谢文玲
,
王杉华
金属学报
为开发不需“训练”就具有高可回复形变的铁基形状记忆合金，本文研究了直接时效和形变时效对Fe-13.53Mn-4.86Si-8.16Cr-3.82Ni-0.16C合金第二相析出，马氏体相变和形状记忆效应的影响。扫描电镜和X-Ray衍射分析表明时效后有大量Cr23C6第二相析出，但直接时效后Cr23C6的析出位置是无方向性的，而形变时效后Cr23C6的析出是有方向性的。相同时效时间下，形变时效析出的Cr23C6数量要显著多于直接时效的，且尺寸只有直接时效的一半。直接时效和形变时效都能显著提高合金的形状记忆效应，且都存在一个最佳的时效时间。经过任意相同时间时效后，形变时效后的形状记忆效应显著高于直接时效的。通过控制第二相在奥氏体晶粒内的析出方式，使第二相有方向性析出，可制备出免训练高可回复形变的铁基形状记忆合金。
关键词:
形状记忆合金
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Shape memory effect
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Ageing
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Carbides
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Directional precipitation
何明锭
,
李爽
,
吴晓春
上海金属
对比研究了热作模具钢SDCM钢和H13钢在600℃和650℃下的热稳定性能.利用金相显微镜、扫描电镜和X射线衍射仪分析了SDCM钢在热稳定性试验中的微观组织变化.结果表明:SDCM钢较H13钢热稳定性更好;随着保温时间增加,钢中位错密度降低,且钢硬度与位错密度有直接关系;SDCM钢中VC保持稳定,主要析出M23C6碳化物.
关键词:
热作模具钢
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热稳定性
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位错密度
,
碳化物
何西扣
,
王鲁
,
汪力
,
杨钢
,
刘正东
上海金属
研究了一种新型耐热合金GY200在700 ℃长期时效过程中的组织与性能稳定性.结果表明,在时效过程中,GY200合金的室、高温力学性能的稳定性较好,且时效5 000 h后的综合力学性能较标准热处理态有所提升;时效过程未发现μ相、σ相、P相等TCP有害相析出,碳化物和γ'相未发生明显粗化,组织稳定性较好;MC碳化物非常稳定,W能不断取代Ni、Cr、Co原子进入M23C6型碳化物,促进M23C6型碳化物缓慢析出,且M23C6还会依附于MC表面形核析出;γ '相的粗化速率较缓慢,稳定性较高,长大规律符合L-S-W理论,700℃时效长大粗化方程为γ-3-γ-3 =4.408×10-4t.
关键词:
镍基合金
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长期时效
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γ'相
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碳化物
,
拉伸性能
Limin LIU
,
Shaoqing WANG
,
Hengqiang YE
材料科学技术（英文）
The interface structure, work of adhesion, and bonding character of the polar TiC/Ti interface have been examined by the first-principles density functional plane-wave pseudopotential calculations. Both Ti- and C-terminated interfaces including six different interface structures were calculated, which present quite different features. For the Ti-terminated interface, the interfacial Ti-Ti bond has a strong metallic and weak covalent character; while for the C-terminated interface, the interfacial bond is a strong polar covalent interaction between the Ti-3d and C-2p orbital. The work of adhesion of C-terminated interface is nearly 9 J/m2 stronger than that of the Ti-terminated. It is found that each termination has relatively large work of adhesion, which is consistent with other polar interfaces.
关键词:
First-principles
,
null
,
null
,
null
Zheng LIU
,
Ligang WANG
,
Lai WANG
材料科学技术（英文）
The microstructures, the changing rule of carbon-enriched zone, the diffusion behaviors of elements C and Cr, and the carbide type of 0Cr6Mn13Ni10MoTi/1Cr5Mo dissimilar welded joints after aging at 500℃ for various times and after long-term service in technical practice were investigated by using the optical microscopy, electron probe microanalysis, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The results show that in aging 0Cr6Mn13Ni10MoTi/1Cr5Mo dissimilar welded joints, the main carbides are M3C and a few carbides are M7C3 and M23C6. The M3C carbide decomposition and dissolution with increasing aging time or aging temperature and the anti-diffusion of C and Cr cause the decrease and disappearance of the carbon-enriched zone. The results are different from those of the A302/1Cr5Mo dissimilar welded joints in previous studies.
关键词:
Dissimilar welded joint
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null
,
null
,
null
