<![CDATA[
<body bgcolor="#FFFFFF" text="#000000">
<img src="../../img/00_all/transparent.gif" alt="nitinol, nickel-titanium, niti is the superelastic shape memory alloy. It is used in a flexinol wire, flextube, stent or smart material" width="1" height="1"> <img src="../../img/00_all/transparent.gif" alt="NiTinol, shape memory alloys, memory metal, superelastic, nickel-titanium, Niti, sma, shape memory effect, stent, Gedächtnismetalle, Formgedächtnis, Superelastizität, Flexinol, flextube, actuator alloy, smart material" width="1" height="1">
<div id="Layer1" style="position:absolute; width:334px; height:66px; z-index:1; left: 346px; top: 91px;">
<table width="340" border="0" bgcolor="#F1F1F1">
<tr>
<td width="72"> </td>
<td width="161"><a href="html/01_start/frameset.htm"><img src="../../img/12_editor/memory_logo.gif" alt="Memory Metalle | NiTinol, superelastic shape memory alloys" width="132" height="42" border="0"></a></td>
<td width="93"> </td>
</tr>
<tr>
<td height="36"> </td>
<td><font size="2" face="Verdana, Arial, Helvetica, sans-serif"><br>
<a href="html/01_start/frameset.htm">Wellcome to NiTinol - <br>
</a></font> <a href="html/01_start/frameset.htm"><font size="2" face="Verdana, Arial, Helvetica, sans-serif">the
metal with a mind</font></a></td>
<td> </td>
</tr>
</table>
</div>
<div id="Layer2" style="position:absolute; width:770; height:115px; z-index:2; top: 460px; left: 180px;">
<p><font size="2" face="Verdana, Arial, Helvetica, sans-serif">Memory Metalle
| NiTinol the superelastic nickel-titanium<br>
<br>
nitinol, nickel-titanium, niti is the superelastic shape memory alloy. It is used in a flexinol wire, flextube, stent or smart material<br>
<br>
NiTinol, shape memory alloys, memory metal, superelastic, nickel-titanium, Niti, sma, shape memory effect, stent, Gedächtnismetalle, Formgedächtnis, Superelastizität, Flexinol, flextube, actuator alloy, smart material<br>
</font></p>
<h1> <font size="2" face="Verdana, Arial, Helvetica, sans-serif"><a href="../02_effects/00_overview.htm">Memory
Effects</a></font></h1>
<p><font size="2" face="Verdana, Arial, Helvetica, sans-serif">NiTinol shows
basically three significant effects, which are already widely used in a multitude
of commercial products. All of these effects are based on the same metallurgical
fundamentals on a microscopic scale and lead to different macroscopic behaviour:
one and the same alloy can be very pliable and easy to deform plastically,
but it can also show an amazing amount of pure elastic deformability (superelasticity).
Temperature changes lead to the spectacular thermal shape memory effect. <br>
</font></p>
<h1><font size="2" face="Verdana, Arial, Helvetica, sans-serif"><a href="../05_products/01_overview.htm">Products</a></font>
</h1>
<p><font size="2" face="Verdana, Arial, Helvetica, sans-serif">Wire Available:
0,013mm - 5,0 mm and above in hundreds of different diameters. Tubes Available:
O.D. 0,250mm - 5,0 mm Ribbon Available: 0,050mm x 0,025mm up to 10,1mm x 0,76
mm Thin Sheet Available: min. 0,050 mm thickness and max. 100 mm width Components
Custom specified components made out of tubing, wire or sheet. <br>
</font></p>
<h1><font size="2" face="Verdana, Arial, Helvetica, sans-serif"><a href="html/04_applications/01_medical.htm">Applications</a></font></h1>
<p><font size="2" face="Verdana, Arial, Helvetica, sans-serif">NiTinol is used
in a vast variety of applications in medical implants and instruments. Its
excellent corrosion behaviour together with extraordinary properties open
significant markets and opportunities. About 90% of all medical applications
make use of the superelasticity, the remaining 10% use mainly the martensitic
deformation characteristics.<br>
</font></p>
<h1><font size="2" face="Verdana, Arial, Helvetica, sans-serif"><a href="../03_knowhow/01_alloys.htm">Know-How
</a></font></h1>
<p><font size="2" face="Verdana, Arial, Helvetica, sans-serif"> Alloy N Superelastic
Alloy Superelastic standard alloy, 'colder' than alloy S<br>
(Af ca. -15° C)<br>
Alloy S Superelastic Alloy Superelastic standard alloy, 'softer' than alloy
N<br>
(Af ca. 0° C) <br>
Alloy C Superelastic Alloy Cr-doped superelastic alloy, 'stiffer' than alloy
S and N <br>
Alloy B Actuator Alloy Body temperature alloy<br>
(Af ca. 35° C) <br>
Alloy M Actuator Alloy Actuator Alloy with intermediate transformation temperatures<br>
(Af ca. 65° C) <br>
Alloy H Actuator Alloy High temperature actuator alloy <br>
(Af ca. 95° C) <br>
Flexinol Wire Actuator high fatigue Especially optimized actuator wire with
high fatigue resistance<br>
(Af ca. 100° C)<br>
</font></p>
<h1><font size="2" face="Verdana, Arial, Helvetica, sans-serif"><a href="html/06_prototyping/01_modelling.htm">Prototyping</a></font></h1>
<p><font size="2" face="Verdana, Arial, Helvetica, sans-serif">One important
step during product development with Nitinol alloys is the design and production
of suitable tools for component manufacturing. This is very important because
the NiTinol wire, tubing or sheet has to be fixed on a tool in order to avoid
shape recovery during heat treatment. </font></p>
<p><font size="2" face="Verdana, Arial, Helvetica, sans-serif">Depending on
the cross section of the used material and on the number of parts heat treated
in one fixture, the generated forces from the Nitinol components can be remarkable.
Therfore, the fixtures have show both, a high stiffness together with a low
thermal mass in order to heat up in economic periods of time. </font></p>
<p><font size="2" face="Verdana, Arial, Helvetica, sans-serif">This is exactly
a strength of Memory-Metalle GmbH, who has developed new and effective heat
treatment strategies together with special tool steels. Memory-Metalle GmbH
also supplies this technology to your production line!<br>
</font></p>
<h1><font size="2" face="Verdana, Arial, Helvetica, sans-serif"><a href="html/07_manufact/01_manufacturing.htm">Manufacturing</a></font></h1>
<p><font size="2" face="Verdana, Arial, Helvetica, sans-serif">On a total production
space of about 600 m2 Memory-Metalle GmbH is producing medical instruments
and implants as well as shape memory actuators in large quantities. In the
mechanical workshop the necessary fixtures and tools are manufactured on NC
controlled machines by professional precision mechanics.</font></p>
<p><font size="2" face="Verdana, Arial, Helvetica, sans-serif">Shape setting
and heat treatment of NiTinol components is carried out in different types
of furnaces, ranging from muffel furnaces over tube furnaces up to salt baths
and also fluidized bed furnaces. Besides special spring winding machines,
Memory-Metalle also manufactures NiTinol components in NC-controlled chemical
ablative processes. Furthermore, Memory-Metalle is able to apply different
surface finishing processes such as mechanical and electrochemical polishing
techniques. <br>
On partially automated workplaces, actuators as well as components for medical
instruments are manufactured in large quantities of up to 1000 per day.<br>
</font></p>
<h1><font size="2" face="Verdana, Arial, Helvetica, sans-serif"><a href="html/08_inquiry/01_fb_start.htm">Find
& Buy</a></font></h1>
<h1><font size="2"><a href="html/03_knowhow/04_glossary.asp">Glossary</a></font></h1>
<p> <font size="2" face="Verdana, Arial, Helvetica, sans-serif">Af-Temperature:
Temperature, above which the phase transformation from Martensite to Austenite
is fully completed during heating of the alloy.</font><br>
<font size="2" face="Verdana, Arial, Helvetica, sans-serif"><br>
Actuator: Device made out of a shape memory alloy, which is able to provide
a significant amount of mechanical work due to the occurance of the phase
transformation during heating. Actuation force and displacement are functions
of the actuator geometry and design.</font><font size="2" face="Verdana, Arial, Helvetica, sans-serif"><br>
<br>
Apeak- or Ap-Temperature: Temperature, at which the phase transformation from
Martensite to Austenite shows the maximum of heat flow during heating. The
alloy needs a certain amount of energy (heat flow) to initiate the phase transformation
and to move the phase boundary through the alloy. The maximum is a value which
can be accurately measured in a DSC equipment, whereas the As- and Af-temperature
measurements are sometimes lacking reproduceability.</font><font size="2" face="Verdana, Arial, Helvetica, sans-serif"><br>
<br>
As-Temperature: Temperature, at which the phase transformation from Martensite
to Austenite is initiated during heating of the alloy.</font><font size="2" face="Verdana, Arial, Helvetica, sans-serif"><br>
<br>
Austenite: Crystallographic description of the high temperature phase of a
shape memory alloy, which starts to form during heating of the low temperature
phase Martensite when the As-temperature is passed. The formation of Austenite
is completed above the Af-temperature.</font><font size="2" face="Verdana, Arial, Helvetica, sans-serif"><br>
<br>
Biokompatibility: General expression for the suitability of a material for
use in the human body and in the endogenous fluids. For NiTinol, a multitude
of clinical studies and long clinical history have shown that the biocompatibility
is excellent, especially in terms of cytocompatibility, haemocompatibility,
genocompatibility, and corrosion performance. The most current studies report
that the overall biocompatibility of NiTi alloys is comparable to stainless
steel and Titanium alloys. In some applications, such as stents, recent studies
suggest that the biocompatibility of NiTi alloys may be even superior to stainless
steel.</font><font size="2" face="Verdana, Arial, Helvetica, sans-serif"><br>
<br>
DSC (Differential Scanning Calorimetry): Calorimetric method for the characterization
of a shape memory alloy with respect to its transformation temperatures. The
DSC measures the specific heat flow, which changes constantly during the phase
transformation. The overall accuracy and the ease of usage of the DSC equipment
together with the high reproduceability makes it the most suitable method
for alloy characterization. The main disadvantage of the DSC is the fact,
that material deformation and external load cannot be simulated with this
measurement.</font><font size="2" face="Verdana, Arial, Helvetica, sans-serif"><br>
<br>
Hysteresis: a) thermal hysteresis:<br>
The thermal hysteresis means generally the difference between the Apeak- and
the Mpeak-temperatures. The hysteresis appears during passing of the transformation
temperatures and is affected by a number of parameters (alloy composition,
thermo-mechanical treatment, external load, etc.).<br>
</font><font size="2" face="Verdana, Arial, Helvetica, sans-serif">b) mechanial
hysteresis:<br>
The mechanical hysteresis appears during loading and unloading of a shape
memory component in its high temperature phase above Af. The NiTinol component
shows a large amount of strain during loading, which recovers during unloading.
The necessary force to initiate the transformation during loading is higher
as the released force during unloading.</font><font size="2" face="Verdana, Arial, Helvetica, sans-serif"><br>
<br>
Martensite: Crystallographic description of the low temperature phase of a
shape memory alloy, which starts to form during cooling of the high temperature
phase Austenite when the Ms-temperature is passed. The formation of Martensite
is completed below the Mf-temperature. But the Martensite can also be induced
during loading of the Austenite above Mf. This is related to a large amount
of recoverable strain and is called _Superelasticity>.</font><font size="2" face="Verdana, Arial, Helvetica, sans-serif"><br>
<br>
NiTiNOL: Common trade name for the commercially most important family of shape
memory alloys (NiTi alloys). </font><font size="2" face="Verdana, Arial, Helvetica, sans-serif"><br>
<br>
One way effect<br>
(or 'thermal shape memory'): The one way effect occurs in a shape memory alloy,
which has been deformed below its lower transformation temperature Ms. The
obvious deformation is called pseudoplastic because the alloy recovers shape
during subsequent heating into its austenitic high temperature phase. During
this shape change the shape memory alloy is capable of providing a significant
amount of work output and can be used as an actuator. The subsequent cooling
in to the austenitic phase is normally not subject to a reverse shape change,
as long as there is no external stress during Austenite - Martensite transformation.</font><font size="2" face="Verdana, Arial, Helvetica, sans-serif"><br>
<br>
Phase transformation<br>
(here: martensitic phase transformation): Physical mechanism, which is the
metallurgical basis of the shape memory effect. The term martensitic phase
transformation describes the formation of Martensite during cooling OR during
loading with an external stress of the austenitic high temperature phase.
</font><br>
<font size="2" face="Verdana, Arial, Helvetica, sans-serif"><br>
R-Phase: Phase, which appears under certain conditions in for instance NiTinol
alloys and which is still considered as being a _pre-martensitic>. The
R-phase is related to some anomalies of certain functional properties. The
R-phase transformation shows a very narrow thermal hysteresis, but at the
same time a very small amount of work output. Applications of the R-phase
transformation are very hard to find in the market.</font><br>
<font size="2" face="Verdana, Arial, Helvetica, sans-serif"><br>
</font><font size="2" face="Verdana, Arial, Helvetica, sans-serif"> Superelasticity:
Sometimes compared to a rubber-like deformability of shape memory alloys,
which occurs during application of an external stress on the austenitic high
temperature phase above Af. Thus, the superelastic effect is related to about
8% of recoverable elastic stress, for which temperature changes are not necessary.
The superelasticity occurs basically in the same alloys as the thermal shape
memory (one way effect).</font><br>
<font size="2" face="Verdana, Arial, Helvetica, sans-serif"><br>
Thermomechanical treatment: Treatment of a shape memory alloy consisting out
of a combination between colk working steps and annealing processes. The purpose
of the thermomechanical treatment is the adjusting of a number of functional
properties, like e.g. the phase transformation temperatures. Usually the annealing
of the component or the semi-finished shape is the last step of the fabrication
process.</font><br>
<font size="2" face="Verdana, Arial, Helvetica, sans-serif"><br>
Transformation temperatures: Temperature values, at which start and finish
of the phase transformation can be measured (Ms-, Mf-, As-, Af-temperature).<br>
</font><font size="2" face="Verdana, Arial, Helvetica, sans-serif"><br>
Two way effect: Special form of the thermal shape memory effect, in which
not just the heating but also the cooling of the shape memory element are
subject to shape changes. This effect is induced either by a special thermomechanical
treatment (_Training>) or through external stresses during cooling. For
design and industrial application of actuators this latter option is highly
preferred for as multitude of reasons.</font></p>
<br>
</div>
</body>
]]>