Al-8Ti-2C对Al-P中间合金变质效果的促进作用

研究了自制Al-P中间合金对共晶及过共晶Al-Si的变质作用，发现该Al-P中间合金对共晶及过共晶Al-Si合金都具有优良的变质效果。同时还发现，当铝合金熔体中加入Al-8Ti-2C中间合金时，Al-P中间合金对两类Al-Si合金的变质效果会增强。当Al-24Si合金中TiC含量为0．03％(以Al-8Ti-2C中间合金方式)时，初晶Si的平均尺寸由原来的47μm细化为41μm，最大尺寸由原来的75μm降为55μm；加入Al-P中间合金和TiC颗粒50min后，就可以出现变质效果，时间再延长，变质效果也不会有更大的提高。当Al-12Si合金中TiC含量为0．03％时，初晶Si的平均尺寸由原来的50μm变为30μm。     

Al-Si-P master alloy and its modification and refinement performance on Al-Si alloys

An Al-Si-P master alloy has been developed by an in-situ reaction and the electron probe microanalyzer (EPMA) results show that there are many pre-formed AlP particles contained in the master alloy. Silicon introduced into the system plays an important role in remarkably im-proving the distribution and content of AlP particles due to their similar crystal structure and lattice parameters. ZL109 alloys have shown fast modification response to the addition of 0.5% Al-15Si-3.SP master alloy at 720℃, with a mass of primary Si precipitating in size of about 15 μm. Also, coarse primary Si grains in Al-30Si alloy can be refined dramatically from 150 μm to 37 μm after the addition of 2.0% Al- 15Si-3.5P master alloy at 850℃. The P recovery of the Al-15Si-3.5P master alloy is much higher than that of a Cu-8.SP master alloy due to the pre-formed AlP particles.     

Al-5Ti-1B对Al-Si合金磷变质行为影响机理的研究

研究了熔炼条件及Al-5Ti-1B中间合金加入量对P变质ZL109合金凝固组织的影响，并着重对其影响机理进行了探讨。结果发现在中频感应炉熔炼条件下，加入适量Al-5Ti-1B对初晶硅有明显的细化作用，而在静置炉（电阻炉）熔炼条件下，这种作用却不明显；同时发现，无论是在电阻炉还是感应炉熔炼条件下，加入过量的Al-5Ti-1B都会使合金中的初晶硅粗化。EPMA分析发现，加入Al-5Ti-1B后合金的初晶硅中心有Ti元素富集。分析认为Al-5Ti-1B中的TiB：粒子对AlP质点具有吸附作用，从而对Al-P中间合金的变质效果产生影响。     

Al-5Ti-1B和Al-P中间合金对Al-Si合金的联合变质作用

研究了Al-5Ti-1B和Al-P中间合金对Al-Si活塞合金组织和性能的影响。结果表明，加入0．2％Al-5Ti-1B中间合金能使经Al-P中间合金变质过的ZL109合金的共晶团和初晶硅进一步细化，抗拉强度也明显提高。随着Al-5Ti-1B加入的增加这种细化作用逐渐减小，当Al-5Ti-1B的加入量为2％时甚至使ZL109中的初晶硅变粗，抗拉强度也随之降低。     

Grain Refining Efficiency of SHS Al-Ti-B-C Master Alloy for Pure Aluminum and Its Effect on Mechanical Properties

A new Al-5Ti-0.75B-0.2C master alloy was successfully prepared by self-propagating high-temperature(SHS)reaction from an Al-Ti-B_4C system with molten Al.Microstructure and phase characterization of the prepared Al-5Ti-0.75B-0.2C master alloy show that the nearly spherical TiC particles,hexagonal or rectangular TiB_2 particles,and blocklike TiAl_3 particles distribute uniformly in the aluminum matrix.Grain refining test on commercial pure aluminum indicates that Al-5Ti-0.75B-0.2C master alloy exhibits a better grain refining performance than Al-5Ti-lB master alloy.By addition of 0.2 wt%Al-5Ti-0.75B-0.2C master alloy,the average grain size of a-Al can be effectively refined to160 ± 5 μm from about 3000 μm,and the tensile strength and elongation are increased by about 20%and 14.1%due to the grain refinement.     

压铸条件下过共晶铝硅合金P变质的必要性

在铝合金压铸生产过程中,Al-P中间合金变质处理和压力铸造工艺都能够使过共晶铝硅合金中的初晶硅晶粒细化.探讨Al-P中间合金变质处理,分别在压铸工艺条件下和普通金属型条件下,对过共晶Al-15Si合金组织的不同影响.试验表明,压铸条件下未经Al-P变质的和经Al-P变质的Al-15Si合金与金属型条件下未经Al-P变质的Al-15Si相比,初晶Si尺寸分别减小50%和75%左右;在相同的压铸工艺条件下,Al-P变质后Al-15Si合金初晶Si尺寸,比未经过Al-P变质的Al-15Si合金初晶Si尺寸减小40%左右.论证了在Al-Si系过共晶铝合金压铸件生产过程中,Al-P中间合金进行变质处理的必要性.     

Effects of individual and combined additions of phosphorus, boron and cerium on primary and eutectic silicon in an Al-30Si alloy

The modification of silicon in an Al-30Si alloy was studied using optical microscopy, electron probe micro-analysis, transmission electron microscopy and differential scanning calorimetry. It is found that phosphorus master alloys combined with boron master alloys have good modification effect on primary silicon but no evident modification effect on eutectic silicon, while boron combined with cerium has good modification effect on eutectic silicon. The results of differential scanning calorimetry show that phosphorus, boron or cerium addition and their combined addition have different undercooling effects on eutectic silicon. Many scholars thought that AlP particles were the nuclei of eutectic silicon when phosphorus was enough in the alloy. Our results show that β-(Al,Si,Fe) can still be the nucleus of plate-like eutectic silicon while AlP is the nucleus of primary silicon when there is enough phosphorus in the melt. In addition, the mechanism about the modification was also discussed.     

Microstructure and refinement performance of Al-Ti-C master alloy: Effect of excess Ti on the growth and nucleating ability of TiC particles

Al-5Ti-0.2C, Al-0.8Ti-0.2C, Al-8Ti-2C, and Al-10Ti master alloys were prepared and used to investigate the influence of excess Ti on the growth of TiC particles and its ability to nucleate Al-grains. The results of a microstructure analysis of TiC-containing alloys and refined CPAl were interrelated to the results of a refinement test. It was found that the presence of excess Ti is essential at the stage of master alloy preparation, as it facilitates the growth and uniform distribution of TiC within the structure. In Al-5Ti-0.2C alloy containing excess Ti, carbide particles grow faster and to a higher extent (from 0.29 μm to 0.44 μm) compared to Al-0.8Ti-0.2C alloy produced without excess Ti (from 0.29 μm to 0.32 μm). The results support the “Ti-transition zone theory” as the mechanism of grain refinement by TiC-containing master alloys. The refinement performance of Al-5Ti-0.2C is superior compared to the one achieved by adding Al-8Ti-2C and Al-10Ti master alloys in corresponding concentrations. For the TiC particles to become favourable nucleating sites, they must undergo certain interaction with excess Ti at the stage of master alloy preparation.     

Al-20％Si中间合金对Al-Si合金共晶Si变质行为的影响

研究了Al-20％Si中间合金对铸造Al-Si合金显微组织的影响.结果表明:向Al-Si合金熔体中加入1％的Al-20％Si中间合金,Al-7％Si合金中的共晶Si由粗大的板片状变为细密的纤维状或点状,变质效果较好,而对共晶Al- 12％Si合金的变质效果较弱;浇注温度对合金显微组织影响较大,适当降低浇注温度,有利于铸件组织的细化;变质温度越低越有利于颗粒状Si相成为形核核心,抑制枝晶组织的形成长大;在变质温度为650℃时,Al-20％Si中间合金对Al-7％Si合金变质有效时间是3h左右.     

Variation of microstructure of RE-containing AlSi20Cu2Ni1RE0.6 alloy with different cobalt contents

Cobalt is generally considered as the element that can promote the high-temperature mechanical properties of Al-Si alloys. In order to develop new hypereutectic Al-Si alloys that can be used at high temperature, the changes of microstructure of Al-20Si-2Cu-1Ni-0.6RE-xCo alloy with different contents of Co were studied in this paper. The results show that, under P-RE complex modification of the alloy melt, the content of Co varying from 0 to 1.5% had little influence on the refining effect of primary Si and modification effect of eutectic Si, but the amount of acicular RE-bearing Al-RE-Ni-Co-Si compounds gradually increased with the increase of Co content. In addition, Co could also modify the morphology of Fe-bearing phases, which solidified as particles instead of long needles. The addition of Co even has an adverse effect on the tensile strength of this RE-containing hypereutectic Al-Si alloy.     

成分互补熔体温度处理对高硅铝合金组织的影响

研究了成分互补熔体温度处理工艺对Al-20Si合金组织的影响规律。研究表明,该工艺能够对高硅铝合金的初生Si相产生明显的变质效果,经成分互补熔体温度处理工艺处理后,初生Si的晶粒在100min内尺寸可稳定在36μm左右,这表明对高硅铝合金的变质效果具有长效性,是一种简单实用的高硅铝合金变质处理工艺。     

Grain refining performance of Al-B master alloys with different microstructures on Al-7Si alloy

The improved halide salt route has been employed to produce Al-3B master alloys with different microstructures. The micro-structural features of AlB₂ particles exhibited different impacts on the grain refining response of Al-7Si alloy, evolving with the holding time after inoculation. Large blocky AlB₂ particles suffer from an intense fading effect while strip-like particles are not effective enough at the 0.005 wt% B addition level. Among the various Al-3B master alloys, sample 1 containing fine, blocky AlB₂ particles was revealed to be the most efficient in refining Al-7Si alloy. With inoculation of only 0.005%B of such alloy, the final grain size of Al-7Si alloy can reach 238 μm. Its grain refining efficiency was more or less retained for holding times up to 60 min.     

原位TiC颗粒对喷射成形Al-Fe-V-Si合金组织和性能影响

通过扫描电镜和透射电镜分析研究了原位反应生成的TiC颗粒对喷射成形态及挤压态的Al-8.5Fe-1.4V-1.7Si合金显微组织的影响,并对合金的力学性能进行了测试。结果表明,原位反应生成的TiC颗粒均匀地分布在合金基体中并细化了基体合金的晶粒,提高了合金的高温组织稳定性;喷射成形Al-8.5Fe-1.4V-1.7Si 3.0TiC合金挤压态的室温和高温强度明显高于喷射成形Al-8.5Fe-1.4V-1.7Si合金挤压态的强度,而且塑性也有明显的提高。     

In Situ Investigation of Si-Poisoning Effect in Al-Cu-Si Alloys Inoculated by Al-5Ti-1B

In situ synchrotron X-radiography was carried out on Al-13Cu and Al-13Cu-7Si alloys with and without addition of Al-5Ti-1B master alloy. The effects of Si content on grain growth and the solute-suppressed nucleation zone (SSNZ) were quantitatively studied. The average grain size can be refined to 164 μm of Al-13Cu alloy inoculated by Al-5Ti-1B. After addition of 7% Si content, a large number of TiB₂ sites in the melt lost the inoculating ability due to “Si poisoning.” The radius of the dendrite tip curvature of Al-13Cu is more than two times as large as that of Al-13Cu-7Si. The sharper tip is able to disperse the solute more effectively and thus grains can grow more rapidly. This causes that the dendrite arm growth rate with addition of 7% Si solute is about 2.6 times that of no Si addition. In addition, the solute enrichment in the SSNZ of Al-13Cu is faster, and the area change of SSNZ is slower than that of Al-13Cu-7Si. Thus more nucleation sites in the SSNZ cannot be activated with addition of Si. This study will shed light on the understanding of Si poisoning in casting Al-Cu-Si alloys.     

Microstructure and mechanical properties of hypereutectic Al-Si alloy modified with Cu-P

The microstructure and mechanical properties of Al-14.6Si castings modified by Cu-P master alloy under different conditions were studied with optical microscope（OM） and mechanical testing and simulation（MTS）.The results indicate that the Cu-P master alloy possesses not only obvious modification effect,but also longevity effect with more than 8 h on the hypereutectic Al-Si alloy.It is shown from thermal calculation,scanning electron microscope（SEM）,and energy dispersive analysis of X-rays（EDAX） that the modification mechanism of Cu-P on primary silicon in the castings is heterogeneous nucleation around AlP particles.The Cu-P master alloy has no or little modifying effect on eutectic silicon,even though it has obvious modification on primary silicon in the castings.This may be because of the fast transformation of eutectic silicon at a very narrow temperature,which will notably weaken the role of AlP particles as heterogeneous nuclei for eutectic silicon.     

Grain refining technique of AM60B alloy by Al-Ti-B master alloy

The effects of grain refining parameters on grain size of AM60B magnesium alloy have been investigated using an Al-5Ti-1B master alloy as refiner; and an appropriate refining technique has been developed. The results indicate that the Al-Ti-B master alloy is an effective grain refiner for AM60B alloy and the grain size can be decreased from 348 μm to 76 μm. Raising the addition temperature or the pouring temperature is beneficial for grain refinement; while for the addition amount and holding time, there is an optimal value. The appropriate grain refining technique is that 0.3% Al-Ti-B master alloy is added at 780oC and then the melt is held for 30 min before pouring. The above phenomena can be explained by the refining mechanisms that have been proposed from the related studies on Al and Mg alloys and theoretical analysis.     

Effects of Si Content and the Addition Amount of Al-3B Master Alloy on the Solidification Structures of Hypoeutectic Al-Si Alloys

Al-Si based cast alloys have become morewidely used in atomobile and aerospace indus-try due to their excellent proPerties, such as highstrength to density ratios, high castability andmachinability and much attention has been fo-cused on this area. Since the discovery [l1 thatAl-4B master alloy could be used to refine A356alloy effectively this phenomenon has arousedmuch attenton and discussion among many in-vestigators [2--13]. Wth resPect to the role thatAl-B tyPe master alloy has played …     

Effects of strontium and boron interactions in Al-7Si alloys

Effects of boron and strontium combined treatment on the microstructure of hypoeutectic Al-7Si alloy have been studied.Experimental results show that strontium has no significant effect on the grain refinement efficiency of boron and the eutectic silicon modification efficiency is not only related to the strontium content but also related to the boron content in the Al-7Si alloy melt.There is a negative interaction between boron and strontium that results in the formation of a strontium-boron-aluminum containing compound,which reduces the effective strontium level and decreases the eutectic silicon modification efficiency substantially.The refinement and modification mechanisms remain unchanged after the combined addition of strontium and boron,Based on the experimental results,a model for assessing the modification level in the Al-Si alloy melts after combined addition of boron and strontium was presented.     

往复挤压Mg-Al-Si合金的高温拉伸性能

利用往复挤压(RE-n,n为挤压道次)制备Mg-4Al-2Si(AS42)、Mg-4Al-4Si(AS44)和Mg-6Al-6Si(AS66)合金,并在150℃和1.33×10-3s-1的初始应变速率下测试合金的拉伸性能。结果表明:RE-8-AS42合金晶粒尺寸为2.1μm,Mg2Si颗粒尺寸为1.3μm;RE-4-AS42合金晶粒尺寸为4.8μm,组织中含有2～20μm的大块Mg2Si颗粒;RE-AS44和RE-AS66合金晶粒尺寸约为11μm,组织中存在>20μm的Mg2Si颗粒。合金拉伸强度随挤压道次增加而提高,RE-8-AS42合金性能最佳,抗拉强度、屈服强度和伸长率分别为250 MPa、197 MPa和62%,高的性能归因于细小的晶粒和阻碍晶界滑移的细小稳定Mg2Si颗粒。