CN1049382A - Alloy containing iron, manganese, silicon and nickel by form memory - Google Patents

Abstract

Fe-Mn-Si-Ni is advantages such as polycrystalline shape memory alloy smelting technology is simple, and cost is low, and cold and hot working is good.In the hot rolling attitude, do not need through any other processing, this alloy can obtain shape memory effect almost completely in-196～50 ℃ of temperature ranges.By certain thermomechanical treatment, its memory performance can obtain obvious improvement.This alloy has high strength, high tenacity, no magnetic is anti-corrosion, anti-low temperature.Thereby, in automatic control, machinofacture, fields such as techniques for ultra-low temperature can be expected to use widely.

Description

Alloy containing iron, manganese, silicon and nickel by form memory

Fe-Mn-Si-Ni is that shape memory alloy belongs to functional materials, structured material, the processing and manufacturing field of no magnetic material.

Shape memory alloy has entered the commercialization stage to a certain extent.Relevant product at home and abroad mainly is by the Ni-Ti memorial alloy at present, and the Cu base memorial alloy is made.These alloys still exist a lot of shortcoming and defect at aspects such as smelting manufacturing process; The Ni-Ti alloy has good memory performance.But this alloy smelting complex process, transformation temperature is restive, costs an arm and a leg; Copper-based memory alloy has remedied the deficiency of Ni-Ti alloy to a certain extent, yet, the machining property of this alloy, the stability of memory performance, and anti-overheated ability is all relatively poor.Fe-Mn-Si be alloy also have good shape memory effect (A.Sato, et al, Acta.Metall.3249847.539).From present report, this alloy also exists poor processability, smelting condition shortcoming such as have relatively high expectations.Thereby above-mentioned alloy is difficult to apply on a large scale to a great extent.

For exploitation has economy, practicality, high-intensity shape memory alloy.The present invention proposes Fe-Mn-Si-Ni is the polycrystalline shape memory alloy.

Shape memory alloy is in certain composition scope, and two kinds of phase transformations take place: a kind of is austenite (r)  martensite (ε) phase transformation, when under the parent phase austenitic state, applies external force.Bring out r → ε and change, produce the strain of macroscopic shape thereupon; After the heating.Reversing change by ε → r is recovered original shape.Promptly produce shape memory effect (being designated as SME); Another kind of phase transformation is that paramagnetic austenite (r)  antiferromagnetic orderization (r) changes.This magnetic transformation suppresses r → ε phase transformation, thereby reduces the memory function of alloy.

When the Fe-Mn-Si-Ni alloy ingredient designs, must take into full account these two kinds of phase transformations to the SME role.When Mn, Ni, Si total content are crossed when low r → ε transformation temperature M _sToo high, this had both worsened the memory performance of alloy, was unfavorable for practical application again.Otherwise Mn, Ni, Si total content are too high, then M _sFar below room temperature, thereby the antiferromagnetic order transition temperature may be higher than room temperature, make parent phase r too stable mutually for stress-induced, therefore also be difficult to obtain good shape memory effect, when one timing of Mn content, the resultant of Si can not be higher than 6%, otherwise will make alloy become very crisp, so that is difficult to processing.Through overtesting and comprehensive, it is considered herein that and when selecting the composition of Fe-Mn base memorial alloy, mainly consider from following several respects.1. avoid stress-induced r → α martensitic transformation.2. improve parent phase intensity.3. suppress the antiferromagnetic order transformation, 4. suppress the martensitic formation of quenching ε, make r be in metastable state.

The Fe-Mn-Si-Ni of the present invention's development is that the alloy ingredient scope is

Mn:22～27% (all by weight percentage)

Si：1～6％

Ni：1～4％

Fe: surplus

C：＜0.02％

S.P total content＜0.01%

O ₂N ₂H ₂Total amount＜200PPm

Alloy adopts electrical induction heating boiler smelting and pouring under normal pressure, behind high temperature homogenizing annealing, becomes the thick sheet material of 7mm in 800～1100 ℃ of forge hots, and then becomes the thick thin plate of 2mm in 1050 ℃ of single hot-rolls.This alloy can also carry out cold rolling or cold group.

Utilize the measurement of sheet sample bending angle to estimate the SME of alloy.With the sheet sample of 1 * 2 * 60mm, on special mould evenly crooked 180 ° connect, its maximum deformation quantity of load face is all greater than 5%.Bent angle after the bending unloading is designated as θ _e, when being heated to temperature T, this bending angle is reduced to θ _T, then the recovery of the shape under the T temperature (SR) is: $\mathrm{SR}=\frac{{\mathrm{\θ}}_e-{\mathrm{\θ}}_T}{{\mathrm{\θ}}_e}\×100\%$ The maximum value of SR is designated as this alloy of SME and presents one way shape-memory effect.Be lower than at 2～3% o'clock at deflection, this alloy without any other thermal treatment, just can obtain SME completely at hot-rolled state.By changing the content of Mn, Si, Ni alloying element.Can in-50～100 ℃ of scopes, regulate control transformation temperature M at an easy rate _s, T _N ^rIn-196～100 ℃ of scopes, impose distortion, all can obtain SME preferably, if hot rolling attitude sample further carries out thermomechanical treatment again.Its memory performance can obtain obvious raising.Distortion  heating cycle Processing Test shows that after few circular treatment, the attenuation trend of the memory performance of alloy just tends towards stability, and in addition, the heating quenching mode is recovered type of heating, and the memory performance of time to this alloy all do not have tangible influence.

This alloy has good room temperature, low temperature, very low temperature mechanical property, at this alloy of room temperature: σ _s=100～140MPa, σ _bThis alloy of=700～900MPa, ＞40～50% is corrosion-resistant, nonmagnetic, temperature coefficient of resistivity dp/dT is little, at T _N ^rNear dp/dT ≈ 0 temperature

The exploitation of Fe-Mn-Si-Ni memorial alloy and research have the meaning of two aspects.On the one hand in theory, its research will further be enriched and shape memory alloy and martensitic transformation theory are improved in development, on the other hand, this alloy has bigger actual application value, at present, why shape memory alloy is difficult to is applied on a large scale, and major cause is memorial alloy manufacturing cost costliness in the past.Estimation roughly.Cu base memorial alloy cost is than low approximately order of magnitude of Ni-Ti alloy, and this alloy only is about 1/3 of a Cu base alloy, and its manufacturing need not special smelting and manufacturing technology.

In sum, Fe-Mn-Si-Ni is that alloy has good memory performance, mechanical property, physicals.Thereby, can in a lot of technical fields, expectation use widely according to performance requriements.For example, in order to making, temperature control element, fastening shockproof bolt, tube stub, precision electrical resistance alloy element, very low temperature do not have magnetic steel member.Be the memory function that example is stressed alloy with Fe-25.38Mn-3,47Si-2.98Ni below, this alloy M _sAbout 50 ℃, antiferromagnetic transition ordering preface temperature T _N ^r=-43 ℃, σ _s=110MPa σ _b/ σ _s=7.89 =60%; When tensile deformation amount≤2%,, behind hot rolling and air cooling,, has SME completely without other any processing-196～25 ℃ of temperature ranges; When the maximum flexibility amount is 5%, SME=80%;

Hot rolling aspect product are through 250 ℃ of tensile pre-deformations 15%, and in 650 ℃ of annealing 10min, the maximum flexibility amount is 5% o'clock then, and the SME under the room temperature can bring up to more than 90%.

Claims (1)

1. shape memory alloy is characterized in that this alloy is made up of following composition

Mn：22-27％

Si：1-6％

Ni：1-4％

Fe: surplus

C：＜0.02％

O ₂N ₂H ₂Total amount＜200ppm.

S.P total content＜0.01%.