Understanding the Co-Poisoning Effect of Zr and Ti on the Grain Refinement of Cast Aluminum Alloys

The “co-poisoning” effect between Zr and Ti (derived from Al-Zr and Al-Ti-B master alloy additions) on the grain refinement of cast aluminum alloys is studied from a crystallographic atom matching viewpoint. The edge-to-edge matching (E2EM) model has been used to investigate the possible “poisoning” phase containing Zr/Ti, Al, and Fe in commercial grade aluminum alloys. The results show that Al₃Ti is the most likely constituent to be poisoned due to the formation of an Al₈Fe₄Zr coating on its surface, since the Al₈Fe₄Zr phase has good crystallographic atom matching with Al₃Ti, but not with the aluminum matrix. Meanwhile, the partial dissolution of Al₃Zr nucleant particles to compensate for the loss of solute Zr aggravates the poisoning phenomenon. This proposed mechanism is consistent with most previous experimental observations and with existing practical solutions employed in the foundry.     

铝及铝合金细化剂的研究

综述了晶粒细化剂的发展历史及细化剂的细化机理和各种细化剂的比较。并着重介绍了新一代的Al-Ti-C晶粒细化剂。     

铝及铝合金细化剂的研究

综述了晶粒细化剂的发展及历史，细化剂的细化机理和各种细化剂的比较。并着重介绍了新一代的AlTiC晶粒细化剂。     

Optimization of Melt Treatment for Austenitic Steel Grain Refinement

Metallurgical and Materials Transactions B - Refinement of the as-cast grain structure of austenitic steels requires the presence of active solid nuclei during solidification. These nuclei can be...     

铝合金熔体温度处理的研究进展

文章介绍了熔体温度处理方法，综述了国内外铝合金熔体温度处理的研究现状，重点阐述了熔体温度处理在Al-Si、Al-Cu合金方面的研究进展，归纳了熔体温度处理对熔体结构和熔体状态的影响。     

Effects of Cooling Rate and Solute Content on the Grain Refinement of Mg-Gd-Y Alloys by Aluminum

The effect of Al additions on grain refinement of Mg-Gd-Y alloys with different solute contents at different cooling rates has been investigated. For all alloys, significant grain refinement was due to the formation of Al₂(Gd _x Y_1?x ) nucleant particles. The number density and size distribution of Al₂(Gd _x Y_1?x ) were affected by both solute content and the cooling rate. Grain sizes (d _gs) of Mg-Gd-Y base alloys and of Mg-Gd-Y-Al alloys were related to solute content (defined by the growth restriction factor, Q), cooling rate ( \( \dot{T} \) ), and area number density (ρ _ns) and size (d _p) of nucleant particles that can be activated. It is found that grain sizes of Mg-Gd-Y base alloys follow the relationship \( d_{\text{gs}} = a + \frac{b}{{Q\sqrt {\dot{T}} }} \) , while grain sizes of Al-refined samples follow the relationship \( d_{\text{gs}} = \frac{a'}{{\sqrt {\rho {}_{\text{ns}}} }} + \frac{b'}{{\sqrt {\dot{T}} Qd_{\text{p}} }} \) , where a, b, a′, and b′ were constants. In addition, the grain refinement effect of Al additions was more susceptible to solute content and the cooling rate than that of Zr which is regarded as the most efficient grain refiner for Mg alloys.     

Microstructures and Grain Refinement of Additive-Manufactured Ti-xW Alloys

Metallurgical and Materials Transactions A - It is necessary to better understand the composition–processing–microstructure relationships that exist for materials produced by additive...     

铝及铝合金晶粒细化剂的研究

综述了铝及铝合金晶粒细化剂的发展历史，阐述了晶粒细化剂的细化机理，对各种细化剂进行了比较，并着重介绍了新一代Al—Ti—C晶粒细化剂。     

Grain Refinement of Alloys in Fusion-Based Additive Manufacturing Processes

Metallurgical and Materials Transactions A - One of the less desirable aspects of fusion-based additive manufacturing is the propensity for coarse columnar grain structures crossing build layers to...     

Grain Refinement by Cyclic Displacive Forward/Reverse Transformation in Fe-High-Ni Alloys

A novel method for grain refinement of martensite structures was proposed, in which transformation strain is accumulated by cyclic displacive forward and reverse transformations. This method can refine martensite structures in an Fe-18Ni alloy because a high density of austenite dislocations is introduced by a displacive reverse transformation in addition to an inheritance of dislocations in body-centered cubic martensite into austenite during cyclic transformation. The addition of a small amount of carbon accelerates structure refinement significantly, which results in the formation of ultra-fine-grained structures after ten cycles.

     

超声溶体处理对7055铝合金铸态组织和性能的影响

通过对7055铝合金熔体浇铸前作用超声，改变凝固前熔体状态．研究超声作用对铸态合金相组织、力学性能的影响。结果表明：在约650℃对7055铝合金熔体作超声处理一定时间后浇铸，能细化晶粒，提高其强度和塑性。     

Role of Remelting in Grain Refinement of Undercooled Single-Phase Alloys

Metallurgical and Materials Transactions A - Bulk and thin samples of Cu75Ni25 (at. pct) alloy were solidified over a range of undercoolings. Unlike the bulk samples, in which grains were...     

铝合金晶粒细化的研究进展与发展趋势

阐述了铝合金晶粒细化技术的研究和应用现状,铝合金获得细晶的几种凝固技术,晶粒细化剂和变质剂的变质细化作用及晶粒细化机理。并叙述了铝合金晶粒细化的发展趋势以及新型Al-Ti-C-Re、Al-Ti-B-Re合金的细化效果及应用。     

Effect of gravity level on grain Refinement in Aluminum Alloys

Metallurgical and Materials Transactions A -     

铝合金管材晶粒度的细化研究

通过控制6063管材截面晶粒尺寸,来满足某高端汽车客户标准中100μm的晶粒尺寸要求;从铸棒的均质制度、模具设计方式、挤压工艺三个方面进行优化控制,通过高倍显微镜、电导率和布氏硬度等检测方法进行深入分析.结果表明,铸棒采用高温短时的均质制度,模具减少前室的设计方法,挤压工艺使用低温快速的挤压方式,成功生产出符合高端汽车...     

Behavior of Boron in Molten Aluminum and its Grain Refinement Mechanism

The mechanism of heterogeneous grain refining of aluminum by ultrafine elemental boron particles was investigated. In order to facilitate the observation of the boron-aluminum interface, a boron filament was introduced in a melt at 1013 K (740 °C) containing different levels of Ti. The Al/B interface was studied using transmission electron microscopy and different phases were identified using the electron diffraction method. The experimental results showed that boron is dissolved in pure aluminum while its dissolution is inhibited in presence of titanium solute. A thin layer of TiB₂ formed at the surface of boron thickens with residence time in the melt. The mechanisms by which aluminum is crystallized on boron are discussed.